Geology and landscape evolution of the Hellas region of Mars

NASA Technical Reports Server (NTRS)

Tanaka, Kenneth L.; Leonard, Gregory J.

1995-01-01

Hellas basin on Mars has been the site of volcanism, tectonism, and modification by fluvial, mass-wasting, and eolian processes over its more than 4-b.y. existence. Our detailed geologic mapping and related studies have resulted in the following new interpretations. The asymmetric distribution of highland massifs and other structures that define the uplifted basin rim suggest a formation of the basin by the impact of a low-angle bolide having a trajectory heading S60E. During the Late Noachian, the basin was infilled, perhaps by lava flows, that were sufficiently thick (greater than 1 km) to produce wrinkle ridges on the fill material and extensional faulting along the west rim of the basin. At about the same time, deposits buried northern Malea Planum, which are interpreted to be pyroclastic flows from Amphitrites and Peneus Paterae on the basis of their degraded morphology, topology, and the application of a previous model for pyroclastic volcanism on Mars. Peneus forms a distinctive caldera structure that indicates eruption of massive volumes of magma, whereas Amphitrites is a less distinct circular feature surrounded by a broad, low, dissected shield that suggests generally smaller volume eruptions. During the Early Hesperian, an approximately 1-to 2km-thick sequence of primarily fined-grained, eolian material was deposited on the floor of Hellas basin. Subsequently, the deposit was deeply eroded, except where armored by crater ejecta, and it retreated as much as 200-300 km along its western margin, leaving behind pedestal craters and knobby outliers of the deposit. Local debris flows within the deposit attest to concentrations of groundwater, perhaps in part brought in by outflow floods along the east rim of the basin. These floods may have deposited approximately 100-200m of sediment, subduing wrinkle ridges in the eastern part of the basin floor. During the Late Hesperian and Amazonian, eolian mantles were emplaced on the basin rim and floor and surrounding highlands. Their subsequent erosion resulted in pitted and etched plains and crater fill, irregular mesas, and pedestal craters. Local evidence occurs for the possible former presence of ground ice or ice sheets approximately 100 km across; however, we disagree with a hypothesis that suggest that the entire south rim and much of the floor of Hellas have been glaciated. Orientations of dune fields and yardangs in lower parts of Hellas basin follow directions of the strongest winds predicted by a recently published general circulation model (GCM). Transient frost and dust splotches in the region are, by contrast, related to the GCM prediction for the season in which the images they appear in were taken.

Ancient Giant Basin/Aquifer System in the Arabia Region, Mars

NASA Technical Reports Server (NTRS)

Dohm, James M.; Barlow, Nadine; Williams, Jean-Pierre; Baker, Victor R.; Anderson, Robert C.; Boynton, William V.; Fairen, Alberto G.; Hare, Trent M.

2004-01-01

Ancient geologic/hydrologic phenomena on Mars observed through the magnetic data [1,2] provide windows to the ancient past through the younger Argyre and Hellas impacts [e.g., 3,4], the northern plains basement [5], and the Tharsis and Elysium magmatic complexes (recently referred to as superplumes [6,7]). These signatures, coupled with highly degraded macrostructures (tectonic features that are tens to thousands of km-long [8]), reflect an energetic planet during its embryonic development (.5 Ga or so of activity) with an active dynamo and magnetosphere [1,2,6]. One such window into the ancient past occurs northwest of the Hellas impact basin in Arabia Terra. Arabia Terra is one of the few water-rich equatorial regions of Mars, as indicated through impact crater [9] and elemental [10,11] information. This region records many unique traits, including stratigraphy, topography, cratering record, structural character, geomorphology, and geophysical, elemental, albedo, and thermal inertia signatures. We interpret these to collectively indicate a possible ancient giant impact basin that later became an important aquifer, as it provided yet another source of water for the formation of putative water bodies that occupied the northern plains [12,13] and addresses possible water-related characteristics that may be observed at the Opportunity landing site. This basin is antipodal to Tharsis and estimated to be at least 3,000 km in diameter.

Complex geomorphologic assemblage of terrains in association with the banded terrain in Hellas basin, Mars

NASA Astrophysics Data System (ADS)

Diot, X.; El-Maarry, M. R.; Schlunegger, F.; Norton, K. P.; Thomas, N.; Grindrod, P. M.; Chojnacki, M.

2016-02-01

Hellas basin acts as a major sink for the southern highlands of Mars and is likely to have recorded several episodes of sedimentation and erosion. The north-western part of the basin displays a potentially unique Amazonian landscape domain in the deepest part of Hellas, called ;banded terrain;, which is a deposit characterized by an alternation of narrow band shapes and inter-bands displaying a sinuous and relatively smooth surface texture suggesting a viscous flow origin. Here we use high-resolution (HiRISE and CTX) images to assess the geomorphological interaction of the banded terrain with the surrounding geomorphologic domains in the NW interior of Hellas to gain a better understanding of the geological evolution of the region as a whole. Our analysis reveals that the banded terrain is associated with six geomorphologic domains: a central plateau named Alpheus Colles, plain deposits (P1 and P2), reticulate (RT1 and RT2) and honeycomb terrains. Based on the analysis of the geomorphology of these domains and their cross-cutting relationships, we show that no widespread deposition post-dates the formation of the banded terrain, which implies that this domain is the youngest and latest deposit of the interior of Hellas. Therefore, the level of geologic activity in the NW Hellas during the Amazonian appears to have been relatively low and restricted to modification of the landscape through mechanical weathering, aeolian and periglacial processes. Thermophysical data and cross-cutting relationships support hypotheses of modification of the honeycomb terrain via vertical rise of diapirs such as ice diapirism, and the formation of the plain deposits through deposition and remobilization of an ice-rich mantle deposit. Finally, the observed gradual transition between honeycomb and banded terrain suggests that the banded terrain may have covered a larger area of the NW interior of Hellas in the past than previously thought. This has implications on the understanding of the evolution of the deepest part of Hellas.

An ice-rich flow origin for the banded terrain in the Hellas basin, Mars

NASA Astrophysics Data System (ADS)

Diot, X.; El-Maarry, M. R.; Guallini, L.; Schlunegger, F.; Norton, K. P.; Thomas, N.; Sutton, S.; Grindrod, P. M.

2015-12-01

The interior of Hellas Basin displays a complex landscape and a variety of geomorphological domains. One of these domains, the enigmatic banded terrain covers much of the northwestern part of the basin. We use high-resolution (Context Camera and High-Resolution Imaging Science Experiment) Digital Terrain Models to show that most of the complex viscous flowing behavior exhibited by the banded terrain is controlled by topography and flow-like interactions between neighboring banded terrain. Furthermore, the interior of the basin hosts several landforms suggestive of the presence of near-surface ice, which include polygonal patterns with elongated pits, scalloped depressions, isolated mounds, and collapse structures. We suggest that thermal contraction cracking and sublimation of near-surface ice are responsible for the formation and the development of most of the ice-related landforms documented in Hellas. The relatively pristine form, lack of superposed craters, and strong association with the banded terrain, suggest an Amazonian (<3 Ga) age of formation for these landforms. Finally, relatively high surface pressures (above the triple point of water) expected in Hellas and summertime temperatures often exceeding the melting point of water ice suggest that the basin may have recorded relatively "temperate" climatic conditions compared to other places on Mars. Therefore, the potentially ice-rich banded terrain may have deformed with lower viscosity and stresses compared to other locations on Mars, which may account for its unique morphology.

Hellas as a Possible Site of Ancient Ice-Covered Lakes on Mars

NASA Technical Reports Server (NTRS)

Moore, Jeffrey M.; Wilhelms, Don E.; DeVincenzi, Donald (Technical Monitor)

2002-01-01

Based on topographic, morphologic, and stratigraphic evidence, we propose that ancient water-laid sediment is the dominant component of deposits within Hellas Planitia, Mars. Multiply layered sediment is manifested by alternating benches and scarps visible in Mars Orbiting Camera narrow-angle (MOC NA) images. Viking Orbiter camera and MOC NA images were used to map contacts and stratigraphically order the different materials units within Hellas. Mar's Orbiting Laser Altimeter (MOLA) data reveal that the contacts of these sedimentary units, as well as a number of scarps or other abrupt changes in landscape texture, trace contours of constant elevation for thousands of km, and in one case all around the basin. Channels, consensually interpreted to be cut by water, lead into the basin. MOLA results indicate that the area encompassed by greater Hellas' highest closed contour is nearly one-fifth that of the entire northern plains, making the Hellas 'drainage' area much larger than previously reported. If lakes formed under climatic conditions similar to the modern Martian climate, they would develop thick ice carapaces, then the lakes would eventually sublimate away. Two units within Hellas exhibit a reticulate or honeycomb pattern we speculate are impressions made by lake-lowered ice blocks grounding into initially soft mud.

Hellas as a possible site of ancient ice-covered lakes on Mars

USGS Publications Warehouse

Moore, Johnnie N.; Wilhelms, D.E.

2001-01-01

Based on topographic, morphologic, and stratigraphic evidence, we propose that ancient water-laid sediment is the dominant component of deposits within Hellas Planitia, Mars. Multiple-layered sediment is manifested by alternating benches and scarps visible in Mars orbiting camera narrow-angle (MOC NA) images. Viking Orbiter camera and MOC NA images were used to map contacts and stratigraphically order the different materials units within Hellas. Mars orbiting laser altimeter (MOLA) data reveal that the contacts of these sedimentary units, as well as a number of scarps or other abrupt changes in landscape texture, trace contours of constant elevation for thousands of km, and in one case all around the basin. Channels, consensually interpreted to be cut by water, lead into the basin. MOLA results indicate that the area encompassed by greater Hellas' highest closed contour is nearly one-fifth that of the entire northern plains, making the Hellas "drainage" area much larger than previously reported. If lakes formed under climatic conditions similar to the modern Martian climate, they would develop thick ice carapaces, then the lakes would eventually sublimate away. Two units within Hellas exhibit a reticulate or honeycomb pattern, which we speculate are impressions made by lake-lowered ice blocks grounding into initially soft mud.

Ancient Giant Basin/Aquifer System in the Arabia Region, Mars, and Its Influence on the Evolution of the Highland-Lowland Boundary

NASA Technical Reports Server (NTRS)

Dohm, J. M.; Barlow, N. G.; Williams, Jean-Pierre; Ferris, J. C.; Miyamoto, H.; Baker, V. R.; Boynton, W. V.; Strom, R. G.; Rodriguez, Alexis; Fairen, Alberto G.

2004-01-01

Ancient geologic and hydrologic phenomena on Mars observed through the magnetic data provide windows to the ancient past through the younger Argyre and Hellas impacts, the northern plains basement and the rock materials that mantle the basement, and the Tharsis and Elysium magmatic complexes (recently referred to as superplumes). These signatures, coupled with highly degraded macrostructures (tectonic features that energetic planet during its embryonic development (0.5 Ga or so of activity) with an active dynamo and magnetosphere. One such window into the ancient past occurs northwest of the Hellas impact basin in Arabia Tern. Arabia Terra is one of the few water-rich equatorial regions of Mars, as indicated I through impact crater and elemental information. This region records many unique characteristics, including predominately Noachian materials, a highland-lowland boundary region that is distinct from other boundary regions, the presence of very few macrostructures when compared to the rest of the cratered highlands, the largest region of fretted terrain on Mars, outflow channels such as Mamers Valles that do not have obvious origins, and distinct albedo, thermal inertia, gravity, magnetic, and elemental signatures.

The global topography of Mars and implications for surface evolution

NASA Technical Reports Server (NTRS)

Smith, D. E.; Zuber, M. T.; Solomon, S. C.; Phillips, R. J.; Head, J. W.; Garvin, J. B.; Banerdt, W. B.; Muhleman, D. O.; Pettengill, G. H.; Neumann, G. A.;

Viking bistatic radar observations of the hellas basin on Mars: preliminary results.

PubMed

Simpson, R A; Tyler, G L; Brenkle, J P; Sue, M

1979-01-05

Preliminary reduction of Viking bistatic radar data gives root-mean-square surface slopes in the Hellas basin on Mars of about 4 degrees on horizontal scales averaged over 10 centimeters to 100 meters. This roughness decreases slightly with position along the ground track, south to north. The dielectric constant in this area appears to be approximately 3.1, greater than the martian average. These values are characteristic of lunar maria and are similar to those found near the Viking lander site in Chryse with the use of Earth-based radar.

Northeast Hellas Landscape

NASA Technical Reports Server (NTRS)

2003-01-01

MGS MOC Release No. MOC2-446, 8 August 2003

This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image of pitted terrain northeast of Hellas Basin shows light-toned outcrops of layered, sedimentary rock, and a valley floor covered by large, dark ripples or small dunes. Similar light-toned sedimentary materials are found throughout the region immediately northeast of Hellas, and in the crater, Terby. The area shown is 3 km (1.9 mi) wide and located near 27.5oS, 281.7oW. Sunlight illuminates the scene from the upper left.

Subaqueous Sediment Remobilization and Development of Syndepositional Deformational Structures on Mars: A Kinematic Approach from the Noachian Terby Crater

NASA Astrophysics Data System (ADS)

Sarkar, R.; Das, P.; Basu Sarbadhikari, A.

2017-12-01

A 2 km thick layered sequence within the Noachian Terby crater ( 174 km diameter, 28.0°S - 74.0°E), located at the Northern rim of Hellas basin, has been re-classified here into three major categories, i.e. mega-slump, debris flows, and turbidites based on sedimentation process. A wide spectrum of deformation structures, such as large scale isoclinal moderately inclined fold, pinch and swells, disharmonic folds, sediment loading structure, normal faults and thrust duplexes, suggest that amplitude of the syndepositional deformation spanned from hydroplastic to brittle domains. These structures provide ample evidences of sediment remobilization in Terby. The dominance of such mass-flow deposits in different stratigraphic horizons indicates that the basin was reactivated in frequent intervals during the filling process. However, an undeformed thinning-up sequence of beds, well exhibited at the basinal-lows, identified as ponded/confined turbidites, indicates that the basin experienced a stable bathymetric condition at the up-dip areas of the mega-slumps. An overall enrichment of phyllosilicates and scarcity of large boulders at the basin margins indicates that the provenance materials were deposited under stable and low-energy condition before being transported and re-deposited within the crater during the Terby impact. We presume that the inter-crater layered terrain of Hellas acted as a provenance of Terby's mass-transport deposits.

Geologic map of MTM -45252 and-45257 quadrangles, Reull Vallis region of Mars

USGS Publications Warehouse

Mest, Scott C.; Crown, David A.

2003-01-01

Mars Transverse Mercator (MTM) quadrangles -45252 and -45257 (latitude 42.5° S. to 47.5°S., longitude 250° W. to 260° W.) cover a portion of the highlands of Promethei Terra east of Hellas basin. The map area consists of heavily cratered ancient highland materials having moderate to high relief, isolated knobs and massifs of rugged mountainous material, and extensive tracts of smooth and channeled plains. Part of the ~1,500-km-long Reull Vallis outflow system is within the map area. The area also contains surficial deposits, such as the prominent large debris aprons that commonly surround highland massifs. Regional slopes are to the west, toward the Hellas basin, as indicated by topographic maps of Mars. Approximately 60 percent of the surface of Mars is covered by rugged, heavily cratered terrains believed to represent the effects of heavy bombardment in the inner solar system about 4.0 billion years ago. Much of this terrain, including that within the map area, records a long history of modification by tectonism, fluvial processes, mass wasting, and eolian activity. The presence of fluvial features to the east of Hellas basin, including Reull Vallis and other smaller channels, has significant implications for past environmental conditions. The degraded terrains surrounding Hellas basin provide constraints on the role and timing of volatile-driven activity in the evolution of the highlands. Current photogeologic mapping at 1:500,000 scale (see also Mest and Crown, 2002) from analysis of Viking Orbiter images complements previous geomorphic studies of Reull Vallis and other highland outflow systems, drainage networks, and highland debris aprons, as well as regional geologic mapping studies and geologic mapping of Hellas basin as a whole at 1:5,000,000 scale. Viking Orbiter image coverage of the map area generally ranges from 160 to 220 m/pixel; the central part of the map area is covered by higher resolution images of about 47 m/pixel. Crater size-frequency distributions have been compiled to constrain the relative ages of geologic units and determine the timing and duration of inferred geologic processes.

Regional-scale stratigraphy of surface units in Tyrrhena and Iapygia Terrae, Mars: Insights into highland crustal evolution and alteration history

USGS Publications Warehouse

Rogers, A.D.; Fergason, R.L.

2011-01-01

The compositional, thermophysical and geologic characteristics of surface units in Iapygia and Tyrrhena Terra (60??E-100??E, 0??-30??S) provide new insights into the compositional stratigraphy of the region. Intercrater plains are dominated by two surface units. The older unit (unit 1) is deficient in olivine and more degraded and likely consists of a mixture of impact, volcanic and sedimentary materials. The younger unit (unit 2) is enriched in olivine, exhibits a resistant morphology and higher thermal inertia, and likely represents volcanic infilling of plains. Units 1 and 2 bear a strong resemblance to those previously mapped in Mare Serpentis, a section of highlands crust located northwest of Hellas Basin. Thus, the two major intercrater plains units are even more widespread than previously thought and therefore likely constitute important components of Mars' highland stratigraphy. Many craters in the region contain high thermal inertia deposits (unit 3) that are compositionally identical to unit 2. These may have formed via volcanic infilling or may represent sedimentary materials that have been eroded from crater walls and lithified. Less common units include olivine and/or pyroxene-rich massifs and crater central peaks. These are primarily found within Hellas Basin rim units and may represent mantle materials brought toward the surface during the Hellas impact. Putative chloride deposits are primarily associated with olivine-deficient surfaces (unit 1) that may be heavily degraded occurrences of unit 2. The observations raise a variety of questions related to Martian crustal evolution and alteration that may have more widespread implications outside the study region. Copyright ?? 2011 by the American Geophysical Union.

Regional-scale stratigraphy of surface units in Tyrrhena and Iapygia Terrae, Mars: insights into highland crustal evolution and alteration history

USGS Publications Warehouse

Rogers, A. Deanne; Fergason, Robin L.

2011-01-01

The compositional, thermophysical and geologic characteristics of surface units in Iapygia and Tyrrhena Terra (60°E-100°E, 0°-30°S) provide new insights into the compositional stratigraphy of the region. Intercrater plains are dominated by two surface units. The older unit (unit 1) is deficient in olivine and more degraded and likely consists of a mixture of impact, volcanic and sedimentary materials. The younger unit (unit 2) is enriched in olivine, exhibits a resistant morphology and higher thermal inertia, and likely represents volcanic infilling of plains. Units 1 and 2 bear a strong resemblance to those previously mapped in Mare Serpentis, a section of highlands crust located northwest of Hellas Basin. Thus, the two major intercrater plains units are even more widespread than previously thought and therefore likely constitute important components of Mars' highland stratigraphy. Many craters in the region contain high thermal inertia deposits (unit 3) that are compositionally identical to unit 2. These may have formed via volcanic infilling or may represent sedimentary materials that have been eroded from crater walls and lithified. Less common units include olivine and/or pyroxene-rich massifs and crater central peaks. These are primarily found within Hellas Basin rim units and may represent mantle materials brought toward the surface during the Hellas impact. Putative chloride deposits are primarily associated with olivine-deficient surfaces (unit 1) that may be heavily degraded occurrences of unit 2. The observations raise a variety of questions related to Martian crustal evolution and alteration that may have more widespread implications outside the study region.

Volcanic Structures Within Niger and Dao Valles, Mars, and Implications for Outflow Channel Evolution and Hellas Basin Rim Development

NASA Astrophysics Data System (ADS)

Korteniemi, J.; Kukkonen, S.

2018-04-01

Outflow channel formation on the eastern Hellas rim region is traditionally thought to have been triggered by activity phases of the nearby volcanoes Hadriacus and Tyrrhenus Montes: As a result of volcanic heating subsurface volatiles were mobilized. It is, however, under debate, whether eastern Hellas volcanism was in fact more extensive, and if there were volcanic centers separate from the identified central volcanoes. This work describes previously unrecognized structures in the Niger-Dao Valles outflow channel complex. We interpret them as volcanic edifices: cones, a shield, and a caldera. The structures provide evidence of an additional volcanic center within the valles and indicate volcanic activity both prior to and following the formation of the outflow events. They expand the extent, type, and duration of volcanic activity in the Circum-Hellas Volcanic Province and provide new information on interaction between volcanism and fluvial activity.

Salt or ice diapirism origin for the honeycomb terrain in Hellas basin, Mars?: Implications for the early martian climate

NASA Astrophysics Data System (ADS)

Weiss, David K.; Head, James W.

2017-03-01

The "honeycomb" terrain is a Noachian-aged cluster of ∼7 km wide linear cell-like depressions located on the northwestern floor of Hellas basin, Mars. A variety of origins have been proposed for the honeycomb terrain, including deformation rings of subglacial sediment, frozen convection cells from a Hellas impact melt sheet, a swarm of igneous batholiths, salt diapirism, and ice diapirism. Recent work has shown that the salt or ice diapirism scenarios appear to be most consistent with the morphology and morphometry of the honeycomb terrain. The salt and ice diapirism scenarios have different implications for the ancient martian climate and hydrological cycle, and so distinguishing between the two scenarios is critical. In this study, we specifically test whether the honeycomb terrain is consistent with a salt or ice diapir origin. We use thermal modeling to assess the stability limits on the thickness of an ice or salt diapir-forming layer at depth within the Hellas basin. We also apply analytical models for diapir formation to evaluate the predicted diapir wavelengths in order to compare with observations. Ice diapirism is generally predicted to reproduce the observed honeycomb wavelengths for ∼100 m to ∼1 km thick ice deposits. Gypsum and kieserite diapirism is generally predicted to reproduce the observed honeycomb wavelengths for ≥ 600-1000 m thick salt deposits, but only with a basaltic overburden. Halite diapirism generally requires approx. ≥ 1 km thick halite deposits in order to reproduce the observed honeycomb wavelengths. Hellas basin is a distinctive environment for diapirism on Mars due to its thin crust (which reduces surface heat flux), low elevation (which allows Hellas to act as a water/ice/sediment sink and increases the surface temperature), and location within the southern highlands (which may provide proximity to inflowing saline water or glacial ice). The plausibility of an ice diapir mechanism generally requires temperatures ≤ 250 K within Hellas in order to reproduce the observed diapir wavelength. Conversely, the viability of the salt diapir mechanism requires sufficiently thick evaporite deposits to accumulate in Hellas (generally ≃1-3 km), which requires the emplacement and evaporation within Hellas of a 14-2045 m global equivalent layer (GEL) of saline water (∼2 × 106 km3 to ∼3 × 108 km3). On the basis of our analysis, we conclude that ice diapirism is more likely due to the thin deposits (∼0.1-1 km thick) and low water volumes required (only 0.3-24 m GEL water), and the potential for either glacial deposits or a frozen ocean to supply the necessary ice. Salt diapirism requires thick evaporite deposits and high water volumes by comparison, and thus appears less likely. Deformation of subglacial sediment: The honeycomb terrain has been proposed to be the imprints of grounded icebergs (comparable to terrestrial wallow pits, which form when an iceberg displaces/deforms the underlying sediment; e.g., Bigg, 2016; Moore and Wilhelms, 2001). Bernhardt et al. (2016a) find this origin unlikely due to the wide distribution of sizes expected and smaller dimensions (widths less than ∼100 m, depths less than 25 m) of these features compared to the relatively consistent (and larger) dimensions of the honeycomb cells. Thermokarst origin:Bernhardt et al. (2016a) explored a thermokarst origin for the honeycomb terrain, wherein loss of pore- or massive-ice in the subsurface by melting or sublimation generates shallow scallop-shaped depressions (which frequently overlap). While the widths of thermokarst features (up to ∼15 km in diameter; e.g., Pewe and Journaux, 1983) appear to be consistent with the cells of the honeycomb terrain, Bernhardt et al. (2016a) do not favor a thermokarst origin based on the shallow depths (few tens of meters) of thermokarst holes and lack of overlap observed for the cells within the honeycomb terrain. Impact melt convection has been proposed to form the honeycomb terrain (Mangold and Allemand, 2003; Kite et al., 2009), wherein convection cells in an immediately post-impact Hellas basin impact melt sea formed and produced the honeycomb terrain when the convection cells cooled and froze. Bernhardt et al. (2016a) find this hypothesis unlikely because thick melt sheets are predicted to form a conductive lid that would prevent the observation of frozen convection cells at the surface (e.g., Cassanelli and Head, 2016a). Bernhardt et al. (2016a) also point out that preservation of convection patterns in impact melt is unlikely to occur because convection ceases before a melt completely solidifies (e.g., Cassanelli and Head, 2016a). Furthermore, no cell-like features have been observed in the melt deposits of comparably large lunar impact basins (e.g., Bernhardt et al., 2016a; Vaughan et al., 2013). Igneous diapirism has been proposed to form the honeycomb terrain (Mangold and Allemand, 2003), wherein swarms of batholiths are intruded into the martian crust and are later exposed at the surface by crustal uplift and erosion. This hypothesis is not favored due to the lack of associated tectonic features in Hellas (Diot et al., 2016), and the observation by Bernhardt et al. (2016a) that terrestrial batholith swarms with pronounced topographic surface expressions have not been observed to occur in such regular dense assemblages. Salt diapirism has been previously explored (but not favored) as the origin for the honeycomb terrain (Mangold and Allemand, 2003; Kite et al., 2009; Diot et al., 2016). Although the dimensions and morphology of the honeycomb terrain are remarkably similar to examples of terrestrial salt diapirism (Fig. 1D and E) (e.g., see Fig. 9 in Bernhardt et al., 2016a and Fig. 8 in Fernandez and Kaus, 2015), these investigators suggested that the lack of brittle deformation features and the large volumes of water required to emplace the evaporitic deposits make a salt diapirism origin unlikely. Diot et al. (2016) noted, however, that brittle deformation features are not expected during "passive" downbuilding of diapirs, wherein diapirs propagate upwards at the same rate as they are buried by sediment (Jackson et al., 1994), and Bernhardt et al. (2016a) note that some terrestrial salt diapirism is associated with more ductile, rather than brittle surface deformation, and so the lack of brittle deformation features may not explicitly preclude a salt diapir origin. Bernhardt et al. (2016a) further suggest that the volume of water necessary to produce the thick salt deposits may be as low as a ∼3.5 m global equivalent layer (GEL) of water (∼506 000 km3), assuming fully saturated saline water, and that such a water volume could have been present and recycled throughout the Noachian period (e.g., Rosenberg and Head, 2015). Bernhardt et al. (2016a) conclude that a salt diapir origin for the honeycomb terrain remains a viable candidate formation hypothesis. They performed a preliminary assessment of the diapir-forming layer thicknesses required to produce the observed diapir wavelengths and found that a salt layer must be at least ∼2 km thick and superposed by an overburden between ∼2 and ∼4 km thick to produce the observed diapir wavelengths.We also note that the elongate morphology of the honeycomb terrain (Fig. 1C) is consistent with a diapir origin. Terrestrial salt diapirs are commonly elongated (Fails et al., 1995, pp. 27; Hudec and Jackson, 2007). Elongation can be caused by (1) the local stress field generated by pre-existing faults, (2) a specific tectonic regime, (3) underlying bed slope, or (4) salt thickness variations (Jackson and Talbot, 1986; Harding and Huuse, 2015), or alternatively (5) by variations in the sedimentation rate forming the overlying layer (Fernandez and Kaus, 2015). Ice diapirism:Diot et al. (2016) and Bernhardt et al. (2016a) assessed whether the honeycomb terrain could alternatively be formed by ice diapirism. While not observed on Earth (likely due to lack of ice confinement; Kite et al., 2009), ice diapirism has been interpreted to have occurred on Europa (Pappalardo et al., 1998; Rathbun et al., 1998; Pappalardo and Barr, 2004) and Triton (Schenk and Jackson, 1993), and could plausibly occur under martian conditions (Brand et al., 2008; Kite et al., 2009). Bernhardt et al. (2016a) suggested that an ice diapirism mechanism would require an ice layer ∼ 1 km thick superposed by overburden deposits up to ∼1 km thick in order to produce diapirism with the observed cell wavelength, on the basis of the reduced density of ice compared with salt (Brand et al., 2008). Bernhardt et al. (2016a) then assessed the viability of ice diapirism by determining whether sufficiently thick layers of ice are thermally stable in the martian subsurface. These authors concluded that an ice diapir-forming layer may be stable to depths up to ∼2 km in the Hellas basin subsurface, and that ice diapirism is thus a viable candidate process to form the honeycomb terrain. In summary, Bernhardt et al. (2016a) concluded that the honeycomb terrain in Hellas may be plausibly formed by either salt or ice diapirism, but they were unable to distinguish between the two scenarios. The salt diapirism hypothesis requires a climate with either temporary or prolonged warm conditions, and large volumes of saline water to flow into Hellas and then evaporate or freeze. The ice diapirism scenario, on the other hand, requires either a predominantly cold climate with intermittent warming periods to produce liquid water in Hellas (which would later freeze), or alternatively, a cold climate with a source of glacial ice to form massive ice to be buried and then eventually form the diapirs. The distinction between salt and ice diapirism in Hellas basin is important because all three origins have different (but major) implications for the ancient martian climate and hydrological cycle. In order to distinguish between a salt or ice diapirism origin for the honeycomb terrain, we expand upon the initial Bernhardt et al. (2016a) analysis by using updated values for (1) the ancient geothermal gradient within the Hellas basin, (2) the overburden thermal conductivity, as well as (3) a wider range of surface temperatures. We also reassess the relationships between diapir wavelength and diapir-forming layer/overburden thicknesses using updated numerical and semi-analytic models (e.g., Fernandez and Kaus, 2015) to provide more specific constraints in combination with thermal modeling. Moreover, we consider the thermal stability of salt layers, due to their similarly low dehydration temperature in some cases (e.g., gypsum has a dehydration temperature of 363 K; Orstroff, 1964; Lager et al., 1984). Here, we reevaluate the thermal stability limits of ice and salt in the martian subsurface (as it relates to diapir cell wavelengths) in order to determine whether salt or ice diapirism is a more plausible candidate formation mechanism for the honeycomb terrain in the Hellas basin.

Geologic map of MTM -40252 and -40257 quadrangles, Reull Vallis region of Mars

USGS Publications Warehouse

Mest, Scott C.; Crown, David A.

2002-01-01

Mars Transverse Mercator (MTM) quadrangles -40252 and -40257 cover a portion of the highlands of Promethei Terra northeast of the Hellas basin. The map area consists of heavily cratered ancient highland materials of moderate to high relief, isolated knobs and massifs of rugged mountainous materials, extensive tracts of smooth and channeled plains, and other surficial deposits. Reull Vallis, an approximately 1,500 km-long outflow channel system, cuts through the southeast corner of the map area. Regional slopes are to the southwest, toward the Hellas basin, as indicated by Martian topographic maps and the orientations of channels along the northeast rim of the Hellas basin. The Martian highlands cover more than 60 percent of the planet's surface and are primarily in the southern hemisphere. Most of the highlands consist of rugged, densely cratered terrains believed to represent the final phase of heavy bombardment in the inner solar system about 4.0 billion years ago. Parts of the Martian highlands show evidence of extensive degradation and modification. The map area shows landforms created by numerous geologic processes, including tectonism, fluvial activity, and mass wasting. The occurrence of fluvial features, such as outflow channels and valley networks, has significant implications for past Martian conditions. Determining the geology of the highlands northeast of the Hellas basin provides a better understanding of the role and timing of volatile-driven activity in the evolution of the highlands. Photogeologic mapping at 1:500,000 scale from analysis of Viking Orbiter images complements geomorphic studies of Reull Vallis and other highland outflow systems, of drainage networks, and of highland debris aprons and regional geologic mapping studies of the highlands at the 1:2,000,000 scale and 1:1,000,000 scale. Crater size-frequency distributions have been compiled to constrain the relative ages of geologic units and determine the timing and extents of the observed geologic processes.

Layered Deposits and Pitted Terrain in the Circum Hellas Region

NASA Technical Reports Server (NTRS)

Moore, J. M.; Howard, A. D.

2005-01-01

Much of the southern highlands has been mantled since the Noachian, including a general blanket of possibly airfall-derived sediment that softens the landscape, the Electris mantle including knobby chaos in several basins, and a variety of deposits that are the subject of this study that share the common characteristics of being generally confined to basins and crater floors and that manifest irregular interior depressions. Many of these features occur in a zone surrounding Hellas. These deposits share the general characteristics of having fairly smooth, nearly planar surfaces and abrupt scarps bordering interior and marginal depressions. Despite these common characteristics, a wide range of morphologies occurs. Several end-members are discussed below. Additional information is included in the original extended abstract.

MOLA Global map of surface gradients on Mars

NASA Technical Reports Server (NTRS)

2000-01-01

Absolute slopes on 30-km baselines indicate the magnitude of typical regional tilts of that scale. The Northern hemisphere is flatter than the South, and shows some linear slope breaks, for example north of Alba Patera (40N, 250E) and the Tharsis province. The major volcanos display flanks slopes of 2.5-5 degrees, comparable to Hawaiian shields. The southwest rim of the Hellas impact basin appears relatively eroded, with shallower typical slopes. A shaded relief map of the topography is overlaid is monochrome.

Resurfacing event observed in Morpheos basin (Eridania Planitia) and the implications to the formation and timing of Waikato and Reull Valles, Mars

NASA Astrophysics Data System (ADS)

Kostama, V.-P.; Kukkonen, S.; Raitala, J.

2017-06-01

The large scale outflow channels of the Hellas impact basin are characteristic to its eastern rim region. Although the majority of the valles are located in the large-scale topographic trough connecting Hesperia Planum and Hellas basin, the most far-reaching of them, Reull Vallis is situated to the south-southeast of this trough cutting through Promethei Terra. Reull Vallis and the general geology of the region has been studied in the past, but new higher resolution image data enables us to look into the details of the features implicating the fluvial history of the region. Photogeological mapping using the available data and extensive crater counting utilizing CTX, HiRISE and HRSC provided new insights to the timing of the regional events and episodes. The study resulted in more detailed age constraints compared to the previous results from Viking images. These calculations and the geological study of the upper WMR system (Waikato Vallis - Morpheos basin - Reull Vallis) region and southern Hesperia Planum enabled us to estimate the time-frame of the (fluid) infilling of this reservoir to a model time period of 3.67-3.52 Ga which is thus also the time of the visible activity of the upper Reull Vallis and Waikato Vallis outflow channels. The results also more explicitly defined the size of previously identified Morpheos basin (confined to the 500-550 m contour lines). We also present a geological analysis of the upper parts of the WMR system, and using the observations and calculations, present an updated view of the evolution of the system and associated region.

Purple Mountain Majesty

NASA Image and Video Library

2015-07-15

NASA Mars Reconnaissance Orbite observed this image of an isolated mountain in the Southern highlands reveals a large exposure of purplish bedrock. Since HiRISE color is shifted to longer wavelengths than visible color and given relative stretches, this really means that the bedrock is roughly dark in the broad red bandpass image compared to the blue-green and near-infrared bandpass images. In the RGB (red-green-blue) color image, which excludes the near-infrared bandpass image, the bedrock appears bluish in color. This small mountain is located near the northeastern rim of the giant Hellas impact basin, and could be impact ejecta. http://photojournal.jpl.nasa.gov/catalog/PIA19854

Geophysics: Timing of the Martian dynamo

NASA Astrophysics Data System (ADS)

Schubert, G.; Russell, C. T.; Moore, W. B.

2000-12-01

On Mars, the strong magnetization in the highland crust of the southern hemisphere and the absence of magnetic anomalies at the Hellas and Argyre impact basins have been taken as signs that the core dynamo that once drove the planet's magnetic field turned off more than 4 billion years (Gyr) ago. Here, we argue instead that the Martian dynamo turned on less than 4 Gyr ago and turned off at an unknown time since then. High spatial resolution magnetometry in both Martian hemispheres is needed to reveal the true history of the Martian dynamo.

Mineralogy of Huygens Basin, Mars: A Transect of Noachian Highlands Crust

NASA Astrophysics Data System (ADS)

Seelos, K. D.; Ackiss, S. E.; Seelos, F. P.; McBeck, J. A.; Buczkowski, D. L.; Hash, C. D.; Viviano, C. E.; Murchie, S. L.

2018-06-01

Huygens crater represents a unique probe of the Noachain crust in the Hellas rim region. We have identified four mineralogic units within a morphologic context to understand the ancient martian highlands.

Impact Constraints on Major Events in Early Mars History

NASA Technical Reports Server (NTRS)

Frey, H. V.

2004-01-01

MOLA data have revealed a large population of "Quasi-Circular Depressions" (QCDs) with little or no visible expression in image data. These likely buried impact basins have important implications for the age of the lowland crust, how that compares with original highland crust, and when and how the crustal dichotomy may have formed. The buried lowlands are of Early Noachian age, likely slightly younger than the buried highlands but older than the exposed (visible) highland surface. A depopulation of large visible basins at diameters 800 to 1300 km suggests some global scale event early in martian history, maybe related to the formation of the lowlands and/or the development of Tharsis. A suggested early disappearance of the global magnetic field can be placed within a temporal sequence of formation of the very largest impact basins. The global field appears to have disappeared at about the time the lowlands formed. It seems likely the topographic crustal dichotomy was produced very early in martian history by processes which operated very quickly. Thus there appears to have been a northern lowland throughout nearly all of martian history, predating the last of the really large impacts (Hellas, Argyre and Isidis) and their likely very significant environmental consequences.

Gullied Depression

NASA Technical Reports Server (NTRS)

2006-01-01

26 February 2006 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows gullies formed in the wall of a depression located on the floor of Rabe Crater west of the giant impact basin, Hellas Planitia. Gullies such as these are common features on Mars, but the process by which they are formed is not fully understood. The debate centers on the role and source of fluids in the genesis of these features.

Location near: 44.1oS, 325.9oW Image width: 3 km (1.9 mi) Illumination from: upper left Season: Southern Summer

Honeycomb-Textured Landforms in Northwestern Hellas Planitia

NASA Image and Video Library

2017-11-28

This image from NASA's Mars Reconnaissance Orbiter (MRO) targets a portion of a group of honeycomb-textured landforms in northwestern Hellas Planitia, which is part of one of the largest and most ancient impact basins on Mars. In a larger Context Camera image, the individual "cells" are about 5 to 10 kilometers wide. With HiRISE, we see much greater detail of these cells, like sand ripples that indicate wind erosion has played some role here. We also see distinctive exposures of bedrock that cut across the floor and wall of the cells. These resemble dykes, which are usually formed by volcanic activity. Additionally, the lack of impact craters suggests that the landscape, along with these features, have been recently reshaped by a process, or number of processes that may even be active today. Scientists have been debating how these honeycombed features are created, theorizing from glacial events, lake formation, volcanic activity, and tectonic activity, to wind erosion. The map is projected here at a scale of 50 centimeters (19.7 inches) per pixel. [The original image scale is 53.8 centimeters (21.2 inches) per pixel (with 2 x 2 binning); objects on the order of 161 centimeters (23.5 inches) across are resolved.] North is up. https://photojournal.jpl.nasa.gov/catalog/PIA22118

Styles and Timing of Volatile-driven Activity in the Eastern Hellas Region of Mars

NASA Astrophysics Data System (ADS)

Crown, D. A.; Bleamaster, L. F., III; Mest, S. C.; Teneva, L. T.

2005-03-01

Current research integrates geologic studies of the basin floor and east rim using Viking Orbiter, Mars Global Surveyor, and Mars Odyssey datasets to provide a synthesis of the history of volatiles in the region.

Traveling Weather Disturbances in Mars Southern Extratropics: Sway of the Great Impact Basins

NASA Technical Reports Server (NTRS)

Hollingsworth, Jeffery L.

2016-01-01

As on Earth, between late autumn and early spring on Mars middle and high latitudes within its atmosphere support strong mean thermal contrasts between the equator and poles (i.e. "baroclinicity"). Data collected during the Viking era and observations from both the Mars Global Surveyor (MGS) and Mars Reconnaissance Orbiter (MRO) indicate that this strong baroclinicity supports vigorous, large-scale eastward traveling weather systems (i.e. transient synoptic-period waves). Within a rapidly rotating, differentially heated, shallow atmosphere such as on Earth and Mars, such large-scale, extratropical weather disturbances are critical components of the global circulation. These wave-like disturbances act as agents in the transport of heat and momentum, and moreover generalized tracer quantities (e.g., atmospheric dust, water vapor and water-ice clouds) between low and high latitudes of the planet. The character of large-scale, traveling extratropical synoptic-period disturbances in Mars' southern hemisphere during late winter through early spring is investigated using a high-resolution Mars global climate model (Mars GCM). This global circulation model imposes interactively lifted (and radiatively active) dust based on a threshold value of the instantaneous surface stress. Compared to observations, the model exhibits a reasonable "dust cycle" (i.e. globally averaged, a more dusty atmosphere during southern spring and summer occurs). In contrast to their northern-hemisphere counterparts, southern synoptic-period weather disturbances and accompanying frontal waves have smaller meridional and zonal scales, and are far less intense synoptically. Influences of the zonally asymmetric (i.e. east-west varying) topography on southern large-scale weather disturbances are examined. Simulations that adapt Mars' full topography compared to simulations that utilize synthetic topographies emulating essential large-scale features of the southern middle latitudes indicate that Mars' transient barotropic/baroclinic eddies are significantly influenced by the great impact basins of this hemisphere (e.g., Argyre and Hellas). In addition, the occurrence of a southern storm zone in late winter and early spring is keyed particularly to the western hemisphere via orographic influences arising from the Tharsis highlands, and the Argyre and Hellas impact basins. Geographically localized transient-wave activity diagnostics are constructed that illuminate fundamental differences amongst such simulations and these are described.

Traveling Weather Disturbances in Mars' Southern Extratropics: Sway of the Great Impact Basins

NASA Astrophysics Data System (ADS)

Hollingsworth, Jeffery L.

2016-04-01

As on Earth, between late autumn and early spring on Mars middle and high latitudes within its atmosphere support strong mean thermal contrasts between the equator and poles (i.e., "baroclinicity"). Data collected during the Viking era and observations from both the Mars Global Surveyor (MGS) and Mars Reconnaissance Orbiter (MRO) indicate that this strong baroclinicity supports vigorous, large-scale eastward traveling weather systems (i.e., transient synoptic-period waves). Within a rapidly rotating, differentially heated, shallow atmosphere such as on Earth and Mars, such large-scale, extratropical weather disturbances are critical components of the global circulation. These wave-like disturbances act as agents in the transport of heat and momentum, and moreover generalized tracer quantities (e.g., atmospheric dust, water vapor and water-ice clouds) between low and high latitudes of the planet. The character of large-scale, traveling extratropical synoptic-period disturbances in Mars' southern hemisphere during late winter through early spring is investigated using a high-resolution Mars global climate model (Mars GCM). This global circulation model imposes interactively lifted (and radiatively active) dust based on a threshold value of the instantaneous surface stress. Compared to observations, the model exhibits a reasonable "dust cycle" (i.e., globally averaged, a more dusty atmosphere during southern spring and summer occurs). In contrast to their northern-hemisphere counterparts, southern synoptic-period weather disturbances and accompanying frontal waves have smaller meridional and zonal scales, and are far less intense synoptically. Influences of the zonally asymmetric (i.e., east-west varying) topography on southern large-scale weather disturbances are examined. Simulations that adapt Mars' full topography compared to simulations that utilize synthetic topographies emulating essential large-scale features of the southern middle latitudes indicate that Mars' transient barotropic/baroclinic eddies are significantly influenced by the great impact basins of this hemisphere (e.g., Argyre and Hellas). In addition, the occurrence of a southern storm zone in late winter and early spring is keyed particularly to the western hemisphere via orographic influences arising from the Tharsis highlands, and the Argyre and Hellas impact basins. Geographically localized transient-wave activity diagnostics are constructed that illuminate fundamental differences amongst such simulations and these are described.

Squiggles in Hellas Planitia

NASA Image and Video Library

2017-10-25

At around 2,200 kilometers in diameter, Hellas Planitia is the largest visible impact basin in the Solar System, and hosts the lowest elevations on Mars' surface as well as a variety of landscapes. This image from NASA's Mars Reconnaisance Orbiter (MRO) covers a small central portion of the basin and shows a dune field with lots of dust devil trails. In the middle, we see what appears to be long and straight "scratch marks" running down the southeast (bottom-right) facing dune slopes. If we look closer, we can see these scratch marks actually squiggle back and forth on their way down the dune. These scratch marks are linear gullies. Just like on Earth, high-latitude regions on Mars are covered with frost in the winter. However, the winter frost on Mars is made of carbon dioxide ice (dry ice) instead of water ice. We believe linear gullies are the result of this dry ice breaking apart into blocks, which then slide or roll down warmer sandy slopes, sublimating and carving as they go. The linear gullies exhibit exceptional sinuosity (the squiggle pattern) and we believe this to be the result of repeated movement of dry ice blocks in the same path, possibly in combination with different hardness or flow resistance of the sand within the dune slopes. Determining the specific process that causes the formation and evolution of sinuosity in linear gullies is a question scientists are still trying to answer. What do you think causes the squiggles? https://photojournal.jpl.nasa.gov/catalog/PIA22052

Using CRISM and THEMIS to characterize high thermal inertia terrains in the northern Hellas region of Mars

NASA Astrophysics Data System (ADS)

McBeck, J.; Seelos, K. D.; Ackiss, S. E.; Buczkowski, D.

2014-12-01

Previous analyses of Thermal Emission Imaging System (THEMIS) data indicate that high thermal inertia (TI) materials within the cratered highlands north of Hellas are in situ bedrock units enriched in olivine. The high TI materials occur in both ~3.5 Ga infilled, flat-floored craters as well as ~3.8-4.0 Ga expanses of intercrater plains. A spatial association of the intercrater plains units with the Hellas ring structures suggests that they may have resulted from magma ascension and eruption via crustal fractures. Infilled craters may have formed after individual impact events triggered decompressional melting and effusive volcanism. Here we examine the mineralogy of both the high TI intercrater plains materials and high TI crater floor materials to the north of Hellas (30°E to 85°E and 7°S to 27°S) using Vis/NIR spectral data from the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM). We report on the spatial distribution and variability of observed mafic minerals (olivine, low-calcium pyroxene, and high-calcium pyroxene) to constrain whether the formation of these outcrops were caused or influenced by a single event (e.g., the Hellas impact), multiple individual events, or by some other means, and to provide overall insight into Noachian/Hesperian crustal evolution of Mars.

Mars - Crustal structure inferred from Bouguer gravity anomalies.

NASA Technical Reports Server (NTRS)

Phillips, R. J.; Saunders, R. S.; Conel, J. E.

1973-01-01

Bouguer gravity has been computed for the equatorial region of Mars by differencing free air gravity and the gravity predicted from topographic variations. The free air gravity was generated from an eighth-order set of spherical harmonic coefficients. The gravity from topographic variations was generated by integrating a two-dimensional Green's function over each contour level. The Bouguer gravity indicates crustal inhomogeneities on Mars that are postulated to be variations in crustal thickness. The Tharsis ridge is a region of thick continental type crust. The gravity data, structural patterns, topography, and surface geology of this region lead to the interpretation of the Tharsis topographic high as a broad crustal upwarp possibly associated with local formation of lower-density crustal material and subsequent rise of a thicker crust. The Amazonis region is one of several basins of relatively thin crust, analogous to terrestrial ocean basins. The Libya and Hellas basins, which are probable impact features, are also underlain by thin crust and are possible regions of mantle upwelling.

Orbital evidence for more widespread carbonate-bearing rocks on Mars

NASA Astrophysics Data System (ADS)

Wray, James J.; Murchie, Scott L.; Bishop, Janice L.; Ehlmann, Bethany L.; Milliken, Ralph E.; Wilhelm, Mary Beth; Seelos, Kimberly D.; Chojnacki, Matthew

2016-04-01

Carbonates are key minerals for understanding ancient Martian environments because they are indicators of potentially habitable, neutral-to-alkaline water and may be an important reservoir for paleoatmospheric CO2. Previous remote sensing studies have identified mostly Mg-rich carbonates, both in Martian dust and in a Late Noachian rock unit circumferential to the Isidis basin. Here we report evidence for older Fe- and/or Ca-rich carbonates exposed from the subsurface by impact craters and troughs. These carbonates are found in and around the Huygens basin northwest of Hellas, in western Noachis Terra between the Argyre basin and Valles Marineris, and in other isolated locations spread widely across the planet. In all cases they cooccur with or near phyllosilicates, and in Huygens basin specifically they occupy layered rocks exhumed from up to ~5 km depth. We discuss factors that might explain their observed regional distribution, arguments for why carbonates may be even more widespread in Noachian materials than presently appreciated and what could be gained by targeting these carbonates for further study with future orbital or landed missions to Mars.

Dust and Ice Deposition in the Martian Geologic Record

USGS Publications Warehouse

Tanaka, K.L.

2000-01-01

The polar layered deposits of Mars demonstrate that thick accumulations of dust and ice deposits can develop on the planet if environmental conditions are favorable. These deposits appear to be hundreds of millions of years old, and other deposits of similar size but of greater age in nonpolar regions may have formed by similar processes. Possible relict dust deposits include, from oldest to youngest: Noachian intercrater materials, including Arabia mantle deposits, Noachian to Early Hesperian south polar pitted deposits, Early Hesperian Hellas and Argyre basin deposits, Late Hesperian Electris deposits, and the Amazonian Medusae Fossae Formation. These deposits typically are hundreds of meters to a couple kilometers thick and cover upward of a million or more square kilometers. The apparent persistence of dust sedimentation at the south pole back to the Early Hesperian or earlier and the early growth of Tharsis during the Late Noachian and perhaps earlier indicates that extensive polar wandering is unlikely following the Middle Noachian. A scenario for the overall history of dust and perhaps ice deposition on Mars includes widespread, voluminous accumulations perhaps planetwide during the Noachian as impacts, volcanism, and surface processes generated large amounts of dust; the Arabia deposits may have formed as ice availability and dust accumulation waned. During the Early Hesperian, thick dust sedimentation became restricted to the south pole and the deep Hellas and Argyre basins; the north polar sedimentary record prior to the Amazonian is largely obscured. Deposits at Electris and Medusae Fossae may have resulted from local sources of fine-grained material - perhaps volcanic eruptions.

Basin-forming impacts on Mars and the coupled thermal evolution of the interior

NASA Astrophysics Data System (ADS)

Arkani-Hamed, J.; Roberts, J. H.

2015-12-01

The youngest of the Noachian giant impact basins on Mars, are either weakly magnetized or completely demagnetized, indicating that a global magnetic field was not present and that a core dynamo was not operating at the time those basins formed. Shock heating from this sequence of basin-forming impacts modified the pattern of mantle convection. The heating produced by the eight largest impacts (Acidalia, Amazonis, Ares, Chryse, Daedalia, Hellas, Scopolus, and Utopia) penetrates below the core-mantle boundary (CMB). Here, we extend previous workon coupled thermal evolution into 3D, in order to accurately model the spatial relationship between impact basins. At the time of each impact we introduce a temperature perturbation resulting from shock heating into the core and mantle. Stratification of the core occurs very quickly compared to mantle dynamics, and we horizontally average the temperature in the core.We model mantle convection using the 3D finite element code CitcomS, and the thermal evolution of the core using a 1D parameterization.Each impact alters the pattern of mantle dynamics and a significant amount of impact melt is produced in the near surface. However, only the outermost part of the core is affected; the inner core temperature is still adiabatic. Immediately following the impact, the inner core may remain convective. The top of the core will cool by conduction into the deeper core faster than across the CMB, deepening the zone of stable stratification. Further core cooling results in formation of a convecting zone at the top of the core that propagates downwards as the thermal gradient becomes adiabatic at greater depths. Our goal is to obtain a better estimate of the time scale for restoration of post-impact core dynamo activity. Because the disappearance of the magnetic field exposes the early atmosphere to solar wind activity, constraining the history of the dynamo is critical for understanding climate evolution and habitability of the surface.

Geology of Libya Montes and the Interbasin Plains of Northern Tyrrhena Terra, Mars: First Year Results and Second Year Work Plan

NASA Technical Reports Server (NTRS)

Skinner, J. A., Jr.; Rogers, A. D.; Seelos, K. D.

2010-01-01

The Libya Montes-Tyrrhena Terra highland-lowland transitional zone of Mars is a complex tectonic and erosional region that contains some of the oldest exposed materials on the Martian surface as well as aqueous mineral signatures that may be potential chemical artifacts of early highland formational processes. Our 1:1M scale mapping project includes the geologic materials and landforms contained within MTMs 00282, -05282, -10282, 00277, - 05277, and -10277, which cover the highland portion of the transitional zone. The map region extends from the Libya Montes southward into Tyrrhena Terra and to the northern rim of Hellas basin and includes volcanic rocks of Syrtis Major Planum and a broad lowlying plain (palus) that forms a topographic divide between Isidis and Hellas basins. The objective of this project is to describe the geologic history of regional massif and plains materials by combining geomorphological and compositional mapping observations. This abstract summarizes the technical approaches and interim scientific results of Year 1 efforts and the expected work plan for Year 2 efforts.

Tidal Excitation of the Core Dynamo of Mars

NASA Astrophysics Data System (ADS)

Seyed-Mahmoud, B.; Arkani-Hamed, J.; Aldridge, K.

2007-05-01

The lack of magnetic anomalies inside the giant impact basins Hellas, Isidis, Utopia and Argyre, inside the northern low lands, over the Tharsis bulge, and over the Tharsis and Olympus mounts suggests that the core field of Mars ceased to exist by about 4 Gyr ago, almost when the giant basins were formed. On the other hand, the giant basins are located on a great circle, implying that the basins were likely produced by fragments of a large asteroid that broke apart as it entered the Roche limit of Mars. This scenario offers a causative relationship for the apparent coincidence of the formation of the giant basins and the cessation of the core dynamo. We suggest that the core dynamo was excited by tidally driven elliptical instability in the Martian core. The breaking of the asteroid and its final impact on Mars eliminated the excitation and thus killed the dynamo. We show that a retrograde asteroid captured in a Keplerian orbit around Mars at a distance of about 50,000-100,000 km could orbit Mars for several hundreds of millions of years before impacting the planet due to the tidal coupling of the asteroid and Mars. Because of relatively very short growth time of the elliptical instability, less than 50,000 years, the asteroid was capable of retaining the elliptical instability and energizing the core dynamo for a geologically long period prior to 4 Ga. Our laboratory observations of a parametric instability of a rotating incompressible fluid, contained in a flexible-walled spherical cavity, confirm the possibility that an early Martian dynamo could have been powered by tidal straining.

Large-Scale Weather Disturbances in Mars’ Southern Extratropics

NASA Astrophysics Data System (ADS)

Hollingsworth, Jeffery L.; Kahre, Melinda A.

2015-11-01

Between late autumn and early spring, Mars’ middle and high latitudes within its atmosphere support strong mean thermal gradients between the tropics and poles. Observations from both the Mars Global Surveyor (MGS) and Mars Reconnaissance Orbiter (MRO) indicate that this strong baroclinicity supports intense, large-scale eastward traveling weather systems (i.e., transient synoptic-period waves). These extratropical weather disturbances are key components of the global circulation. Such wave-like disturbances act as agents in the transport of heat and momentum, and generalized scalar/tracer quantities (e.g., atmospheric dust, water-vapor and ice clouds). The character of large-scale, traveling extratropical synoptic-period disturbances in Mars' southern hemisphere during late winter through early spring is investigated using a moderately high-resolution Mars global climate model (Mars GCM). This Mars GCM imposes interactively lifted and radiatively active dust based on a threshold value of the surface stress. The model exhibits a reasonable "dust cycle" (i.e., globally averaged, a dustier atmosphere during southern spring and summer occurs). Compared to their northern-hemisphere counterparts, southern synoptic-period weather disturbances and accompanying frontal waves have smaller meridional and zonal scales, and are far less intense. Influences of the zonally asymmetric (i.e., east-west varying) topography on southern large-scale weather are examined. Simulations that adapt Mars’ full topography compared to simulations that utilize synthetic topographies emulating key large-scale features of the southern middle latitudes indicate that Mars’ transient barotropic/baroclinic eddies are highly influenced by the great impact basins of this hemisphere (e.g., Argyre and Hellas). The occurrence of a southern storm zone in late winter and early spring appears to be anchored to the western hemisphere via orographic influences from the Tharsis highlands, and the Argyre and Hellas impact basins. Geographically localized transient-wave activity diagnostics are constructed that illuminate dynamical differences amongst the simulations and these are presented.

The main sources of pollution of the aquatic environment in Hellas

NASA Astrophysics Data System (ADS)

Koumantakis, J.; Dimitrakopoulos, D.; Markantonis, K.; Grigorakou, E.; Vassiliou, E.

2003-04-01

The research team of the laboratory of Engineering Geology &Hydrogeology of NTUA and P.P.C. have carried out several research projects since 1990. The conclusions of these projects for the main sources of pollution of the aquatic environment in Hellas are the following: Human activities : a) Urban and industrial wastes (solid and liquids) are disposed or discharged to the surface or groundwater bodies causing degradation of their quality (case studies of Athens Basin, Lavrio region, Atalanti plain), b) intensive use of pesticides and fertilizers for agriculture, through the process of percolation or leaching causes the deterioration of aquifers and surface water (case studies of Plolemais Basin, Korinth region, Elassona Basin, Atalanti plain, Thrapsana Basin Iraklio), c) current exploitations and old or abandoned mining sites, disturb the aquatic environment and create new hydraulic connections between clean and polluted aquifers or the sea (case studies of Lavrio region, Ptolemais Basin, Megalopoli Basin), d) over-pumping of aquifers mainly for irrigation but also in some cases for dewatering of mines, results in continues drawdown of the groundwater level and intrusion of sea (case studies of Korinth region, Athens basin, Naxos island, Nea Peramos Kavala, Marathon, Argolida Field, Atalanti plain, Achaia region, Stratoni area Chalkidiki, Gouves Iraklio). Geological Environment: a) extensive karstification of limestones that spread up all over the Greek region (33%) causes the intrusion of the sea far into the land (case studies of Lavrio region, Kefalonia island, Hymettus mountain), b) the chemical composition of the geological formations through the process of ion exchange and solubility pollute the groundwater resources (case studies of Vegoritis Basin, Katsika Chalkidiki, Florina region). The proposed measures to face these problems are : - the orthological management of the water resources - the artificial recharge of the aquifers, - proper waste management, of wastes generated by human activities, - systematic study of the karstic saline springs of Greece for their exploitation.

Regional Topographic Properties of Pluto and Charon from New Horizons

NASA Astrophysics Data System (ADS)

Schenk, P.; Beyer, R. A.; Moore, J. M.; Spencer, J. R.; McKinnon, W. B.; Weaver, H. A., Jr.; Young, L. A.; Olkin, C.; Ennico Smith, K.; Stern, A.

2016-12-01

Topographic mapping was among the high priority observations for both Pluto and Charon, and as a result these are the best characterized icy bodies outside of Ceres and the Saturn system in terms of topography. Roughly 30-40% of each body was mapped in stereo, resulting in high-quality DEM mapping coverage of both at vertical resolutions of 100-500 m and spatial scales of 300-800 m. On Charon, stereo mapping reveals the rolling topography of Vulcan Planum and its marginal "moat" depressed several hundred meters. The older cratered plains are also broken into large blocks 100-300 km across, separated by extensional troughs 1-3 km deep. Total relief across Charon exceeds 15 km, making it one of the most rugged midsize icy bodies outside Iapetus. Pluto is divided into several distinct geologic provinces, each with its own topographic character. The globally highest features are the elevated bladed terrain plateaus standing 2-3 km high. Cratered plains to the northwest have low relief of a few hundred meters, except for 2-3 km deep unmodified extensional fractures. Etched or eroded plains to the east have local relief of 2-3 km. The most dominant feature is the 3-km deep elliptical basin associated with the nitrogen-rich ice plains of Sputnik Planitia (informally named). This depression most obviously resembles large impact basins on other bodies, most notably Hellas basin on Mars and Caloris basin on Mercury. The basin has a raised rim in some quadrants but is very ancient and eroded and primary impact textures are now lost. Nonetheless, a low-velocity oblique impact remains the most likely explanation for this feature, leaving a depression that became the focus for subsequent volatile ice accumulation.

Buried and Visible Impact Basin Distribution on Mars: Comparison with Magnetization, Gravity and Crustal Thickness Models

NASA Technical Reports Server (NTRS)

Frey, Herbert

2003-01-01

The large population of buried impact basins found in MOLA elevation data on Mars provides compelling evidence for a pre-Noachian crust below the oldest visible Early Noachian surface units, and lowland crust below the younger plains that is Early Noachian in age, older than much of the visible highlands, but not as old as the buried pre-Noachian highlands. The large (D greater than 200 km) buried basins are suggested by Quasi-Circular Depressions (QCDs) that are not apparent in image data, and include features up to 3000 lun diameter in both the lowlands (Utopia) and highlands (a newly found "Ares Basin"). There are about a dozen QCDs larger than 1000 km diameter. We have placed these large features in a relative age sequence based on superimposed smaller QCD. Only the youngest and most obvious of these (Hellas, Argyre, Isidis) lack magnetic anomalies within their main rings. These all have an N(200) cumulative crater density of less than 2.5. Somewhat older lowland-making basins (Utopia, Chryse, Acidalia) with an N(200) age of approximately 3.0, have weak magnetic anomalies, and the oldest, most subdued basins (including Ares) with N(200) greater than 3.5 have many strong magnetic anomalies within their main ring. These older basins likely formed before the main magnetic field died. We have compared our inventory of large QCDs with the distribution of gravity anomalies and with a crustal thickness model which shows many roughly circular areas of thinner crust completely or partly surrounded by narrow regions of thicker crust. These have the structure expected for impact basins, and many of them do correspond to the visible or buried QCDs we previously identified. But there are cases where the crustal thickness feature is offset from the QCD found in topography alone, and there are also several, sometimes large examples of such features which do not coincide with QCDs previously identified. For example, we find several likely buried basins revealed in the crustal thickness data in the Arcadia and Amazonis regions which we did not previously identify, including several features in the 600-1200 km diameter range.

HUBBLE WATCHES THE RED PLANET AS MARS GLOBAL SURVEYOR BEGINS AEROBRAKING

NASA Technical Reports Server (NTRS)

2002-01-01

his NASA Hubble Space Telescope picture of Mars was taken on Sept. 12, one day after the arrival of the Mars Global Surveyor (MGS) spacecraft and only five hours before the beginning of autumn in the Martian northern hemisphere. (Mars is tilted on its axis like Earth, so it has similar seasonal changes, including an autumnal equinox when the Sun crosses Mars' equator from the northern to the southern hemisphere). This Hubble picture was taken in support of the MGS mission. Hubble is monitoring the Martian weather conditions during the early phases of MGS aerobraking; in particular, the detection of large dust storms are important inputs into the atmospheric models used by the MGS mission to plan aerobraking operations. Though a dusty haze fills the giant Hellas impact basin south of the dark fin-shaped feature Syrtis Major, the dust appears to be localized within Hellas. Unless the region covered expands significantly, the dust will not be of concern for MGS aerobraking. Other early signs of seasonal transitions on Mars are apparent in the Hubble picture. The northern polar ice cap is blanketed under a polar hood of clouds that typically start forming in late northern summer. As fall progresses, sunlight will dwindle in the north polar region and the seasonal polar cap of frozen carbon dioxide will start condensing onto the surface under these clouds. Hubble observations will continue until October 13, as MGS carefully uses the drag of the Martian atmosphere to circularize its orbit about the Red Planet. After mid-October, Mars will be too close to the Sun, in angular separation, for Hubble to safely view. The image is a composite of three separately filtered colored images taken with the Wide Field Planetary Camera 2 (WFPC2). Resolution is 35 miles (57 kilometers) per pixel (picture element). The Pathfinder landing site near Ares Valles is about 2200 miles (3600 kilometers) west of the center of this image, so was not visible during this observation. Mars was 158 million miles (255 million kilometers) from Earth at the time. [LEFT] An image of this region of Mars, taken in June 1997, is shown for comparison. The Hellas basin is filled with bright clouds and/or surface frost. More water ice clouds are visible across the planet than in the Sept. image, reflecting the effects of the changing season. Mars appears larger because it was 44 million miles (77 million kilometers) closer to Earth than in the September image. Credit: Phil James (Univ. Toledo) and Steve Lee (Univ. Colorado), and NASA

Evidence for Weak Crustal Magnetic Fields over the Hellas, Chryse, and Acidalia Planitiae

NASA Astrophysics Data System (ADS)

Lee, C. O.; Mitchell, D. L.; Lillis, R.; Lin, R. P.; Reme, H.; Cloutier, P. A.; Acuna, M. H.

2003-04-01

The Electron Reflectometer (ER) onboard Mars Global Surveyor (MGS) detected a plasma boundary between the ionosphere and the solar wind as the latter is diverted around and past the planet [Mitchell et al., GRL, 27, 1871, 2000; Mitchell et al., JGR, 106, 23419, 2001]. Above this boundary the 10-1000 eV electron population is dominated by solar wind electrons, while below the boundary it is dominated by ionospheric photoelectrons. This "photoelectron boundary", or PEB, is sensitive to pressure variations and moves vertically in response to changes in the ionospheric pressure from below and the solar wind pressure from above. The PEB is also sensitive to crustal magnetic fields, which locally increase the total ionospheric pressure and positively bias the PEB altitude. We have empirically modeled and removed systematic variations in the PEB altitude associated with the solar wind interaction, thus isolating perturbations caused by crustal magnetic fields. A map of the PEB altitude perturbations closely resembles maps of the horizontal component of the crustal magnetic field measured at 400 km by the MGS Magnetometer (MAG). We find a PEB altitude bias over the Hellas basin that is consistent with a horizontal magnetic field with an intensity of several nanotesla at 400 km altitude. This is compatible with upper limits to the horizontal crustal field strength set by MGS MAG measurements. Since there is no evidence for significant crustal magnetic sources within the basin from MAG data obtained during aerobraking [Acuna et al. Science, 284, 790, 1999] or from electron reflection data obtained in the mapping orbit [Lillis et al., this conference], the most likely explanation is that the observed horizontal field originates from sources around the Hellas perimeter. No detectable PEB or magnetic signature is observed over the younger Argyre and Isidis Basins. There is also evidence for a significant enhancement (several nanoteslas) in the crustal field strength over Chryse Planitia and much of Acidalia Planitia, which are thought to contain hundreds of meters of material from the main outflow channels on Mars [Carr, Lunar Planetary Sci., 18, 155, 1987]. These fields appear to extend northward from a group of crustal magnetic sources along the dichotomy boundary that were mapped by the MGS Magnetometer.

The distribution of lobate debris aprons and similar flows on Mars

NASA Technical Reports Server (NTRS)

Squyres, S. W.

1979-01-01

Planet-wide mapping of lobate debris aprons and other similar flows on Mars shows a strong concentration in two latitudinal bands roughly 25 deg wide and centered at 40 deg N and 45 deg S. This distribution supports the idea that these flows form when erosional debris is transported downslope and becomes mixed with ice deposited from the atmosphere, as these latitudes should receive high seasonal H2O frost deposition relative to the rest of the planet. Flows are found in the northern hemisphere band wherever old highland surfaces occur but are found in the southern hemisphere only near the two major impact basins, Argyre and Hellas. These areas are apparently characterized by mass wasting that is rapid relative to most of the southern hemisphere highlands. The rate of mass wasting may be related to the degree of consolidation of highland material.

Reull Valles in Approximately Natural Color

NASA Technical Reports Server (NTRS)

1995-01-01

Reull Valles, conspicuous southeast-trending fretted channel, dissects wall deposits of the large Hellas impact basin. Center of picture is at latitude 42 degrees S. longitude 258 degrees. Fretted channels are wide, flat-floored channels with steep walls, which may be runoff channels that have been modified and enlarged by mass wasting. Many nearby hills and mountains are surrounded by lobate debris aprons, which may have formed by slow creep of rock deposits aided by the presence of near-surface ice. Layering is exposed in the channel and crater walls. The color variations of the surface are very bland in this region; most of the variations seen in the enhanced-color version (PIA00153) are due to atmospheric scattering. Viking Orbiter Picture Numbers 126A08 (violet), 126A16 (green), and 126A24 (red) at 157 m/pixel resolution. Picture width is 161 km. North is 112 degrees clockwise from top.

Inversion of Gravity and Magnetic Field Data for Tyrrhena Patera

NASA Technical Reports Server (NTRS)

Milbury, C.; Schubert, G.; Raymond, C. A.; Smrekar, S. E.

2011-01-01

Tyrrhena Patera is located to the southeast/northeast of the Isidis/Hellas impact basin. It was geologically active into the Late Amazonian, although the main edifice was formed in the Noachian(approximately 3.7-4.0 Ga). Tyrrhena Patera and the surrounding area contain gravity and magnetic anomalies that appear to be correlated. The results presented here are for the anomalies 1a and 1b (closest to Tyrrhena Patera), however other anomalies in this region have been modeled and will be presented at the conference.The Mars Global Surveyor (MGS) free-air gravity signature of Tyrrhena Patera has been studied by Kiefer, who inferred the existence of an extinct magma chamber below it. The magnetic signature has been mapped by Lillis R. J. et al., who compared electron reflectometer data, analogous to the total magnetic field, for Syrtis Major and Tyrrhena Patera and argued for demagnetization of both volcanoes.

Pitted Landforms in Southern Hellas Planitia

NASA Image and Video Library

2015-03-25

This image is of a portion of the Southern plains region within Hellas, the largest impact basin on Mars, with a diameter of about 2300 kilometers 1400 miles, as observed by NASA Mars Reconnaissance Orbiter. There are three main phenomena apparent in this image. First, the faint dark streaks that criss-cross the terrain are dust devil tracks that clear the bright dust along their way. Second, the subtle overall bumpy "basketball" texture of the surface is formed by repeated seasonal freezing and thawing of the ice-rich regolith and is common at higher latitudes. Third, the large, elliptical, scalloped depressions are common in permafrost terrains in both hemispheres, where thick, latitude-dependent sedimentary mantles comprise the surface units. These mantles are composed of ice-rich sediments that degrade as the ice sublimates away and is heated either by the Sun or by locally higher geothermal gradients. Sublimation, or the direct change in phase from ice to gas, occurs on Mars because of its low density atmosphere. These depressions have steeper pole-facing slopes, whereas the equator-facing slopes gently fade into the surrounding terrain. At full resolution (see close up view), numerous sublimation pits and networks of polygonal cracks are visible on the steeper, unstable pole-ward facing slopes. The overall morphology of this terrain is characteristic of what is called "thermokarstic degradation processes," which is a term used to describe the formation of pits in an ice-rich terrain due to loss of ice creating pits and collapse features. http://photojournal.jpl.nasa.gov/catalog/PIA19350

Hubble Watches the Red Planet as Mars Global Surveyor Begins Aerobraking

NASA Technical Reports Server (NTRS)

1997-01-01

[RIGHT] This NASA Hubble Space Telescope picture of Mars was taken on Sept. 12, one day after the arrival of the Mars Global Surveyor (MGS) spacecraft and only five hours before the beginning of autumn in the Martian northern hemisphere. (Mars is tilted on its axis like Earth, so it has similar seasonal changes, including an autumnal equinox when the Sun crosses Mars' equator from the northern to the southern hemisphere).

This Hubble picture was taken in support of the MGS mission. Hubble is monitoring the Martian weather conditions during the early phases of MGS aerobraking; in particular, the detection of large dust storms are important inputs into the atmospheric models used by the MGS mission to plan aerobraking operations.

Though a dusty haze fills the giant Hellas impact basin south of the dark fin-shaped feature Syrtis Major, the dust appears to be localized within Hellas. Unless the region covered expands significantly, the dust will not be of concern for MGS aerobraking.

Other early signs of seasonal transitions on Mars are apparent in the Hubble picture. The northern polar ice cap is blanketed under a polar hood of clouds that typically start forming in late northern summer. As fall progresses, sunlight will dwindle in the north polar region and the seasonal polar cap of frozen carbon dioxide will start condensing onto the surface under these clouds.

Hubble observations will continue until October 13, as MGS carefully uses the drag of the Martian atmosphere to circularize its orbit about the Red Planet. After mid-October, Mars will be too close to the Sun, in angular separation, for Hubble to safely view.

The image is a composite of three separately filtered colored images taken with the Wide Field Planetary Camera 2 (WFPC2). Resolution is 35 miles (57 kilometers) per pixel (picture element). The Pathfinder landing site near Ares Valles is about 2200 miles (3600 kilometers) west of the center of this image, so was not visible during this observation. Mars was 158 million miles (255 million kilometers) from Earth at the time.

[LEFT]

An image of this region of Mars, taken in June 1997, is shown for comparison. The Hellas basin is filled with bright clouds and/or surface frost. More water ice clouds are visible across the planet than in the Sept. image, reflecting the effects of the changing season. Mars appears larger because it was 44 million miles (77 million kilometers) closer to Earth than in the September image.

This image and other images and data received from the Hubble Space Telescope are posted on the World Wide Web on the Space Telescope Science Institute home page at URL http://oposite.stsci.edu/pubinfo/

Analysis of Ice-Related Intra-Crater Facies in Promethei Terra, Mars

NASA Astrophysics Data System (ADS)

Orgel, Csilla; Kereszturi, Ákos; van Gasselt, Stephan

2014-05-01

On Mars ice-related landforms have been identified at mid-latitudes between 30° and 50° in both hemispheres including the areas of Tempe Terra, Deuteronilus-Protonilus Mensae, Phlegra Montes and the rims of the southern-hemispheric impact basins Argyre and Hellas [1-7]. Our study area - informally termed hourglass-shaped crater [8] - is located near Reull Vallis on the eastern rim of the Hellas impact basin (39.0°S, 102.8°E). Impact-crater infill was described as debris-covered piedmont-type glacier [8] based on analysis of High Resolution Stereo Camera (HRSC) data, and implies a glacial origin with precipitation of ice during higher obliquity phases. Recent, higher-resolution image data such as data of the High Resolution Imaging Science Experiment (HiRISE) and the Context Imager (CTX) provide a more detailed picture of the lateral distribution of different small-scale surface features indicative of periglacial and/or glacial origin. The aim of this study is to identify qualitative and quantitative characteristics of these ice-related landforms and to separate sources of water ice and related processes. Initial age determinations based on impact-crater size-frequency statistics indicate an age of 3.4 Gyr for the impact-crater and an age of approximately 75 Myr for the infill [8]. In order to identify a possible sequence of surface-feature evolution we calculated the age distribution of four major surface units which span ages ages between 1-47 Myr. Along with detailed age information and a separation of different processes at this confined type location of Mars young-Amazonian landscape evolution and potential cyclic signals are being reconstructed to constrain climate evolution. Carr, M. H. & Schaber, G. G. 1977: Martian permafrost features.- J. Geophys. Res. 82, 4039-4054. Squyres, S. W. 1978: Martian fretted terrain: flow of erosional debris.- Icarus 34, 600-613. Squyres, S. W. 1979: The distribution of lobate debris aprons and similar flows on Mars.- J. Geophys. Res. 84, 8087-8096. Lucchitta, B. K. 1981: Mars and Earth: comparison of cold-climate features.- Icarus 45, 264-303. Lucchitta, B. K. 1984: Ice and debris in the fretted terrain, Mars.- J. Geophys. Res. 89, B409-B418. Squyres, S. W. & Carr, M. H. 1986: Geomorphic evidence for the distribution of ground ice on Mars.- Science 231, 249-252. Kargel, J. S. & Strom, R. G. 1992: Ancient glaciation on Mars.- Geology 20, 3-7. Head, J. W., Neukum, G., Jaumann, R., Hiesinger, H., Hauber, E., Carr, M., Masson, P., Foing, B., Hoffmann, H., Kreslavsky, M., Werner, S., Milkovich, S., van Gasselt, S. & the HRSC Co-Investigator Team 2005: Tropical and mid-latitude snow and ice accumulation, flow and glaciation on Mars.- Nature 434, 346-351.

Hypsometry of lobate debris aprons on the eastern rim of Hellas Basin, Mars: Implications for climate variations

NASA Astrophysics Data System (ADS)

Rutledge, A. M.; Christensen, P. R.

2010-12-01

Geologic features on the surface of Mars show clear evidence of modification by water and water ice at various intervals in the planet’s history. Several studies have demonstrated that buried water ice most likely remains today beneath tens of centimeters of soil. Past obliquity variations are theorized to have promoted the formation and stability of ground ice near the equator, allowing the accumulation of glaciers in the midlatitudes. Potential glacial features, such as lobate debris aprons (LDA) and hourglass craters containing flow features, have also been observed on the eastern rim of Hellas Basin, ranging from latitudes of 30°S to 60°S. LDAs originate at the base of steep massifs and are characterized by lobes of gently sloping, convex-upward surfaces with relatively steep outer margins. The flow-like morphology of these features, including radial and concentric lineations, suggest these features were formed by viscous flow processes. A study targeting the Hellas LDAs by the shallow radar (SHARAD) instrument aboard the Mars Reconnaissance Orbiter (MRO) returned results consistent with massive ice deposits, supporting the hypothesis that these are debris-covered glaciers. These probable glaciers are most likely large reservoirs of present-day, near-surface ice, with implications for global hydrologic cycle modeling, astrobiology studies, and the search for resources in the Solar System. Terrestrial glaciology uses the hypsometric curve, or the empirical cumulative distribution function of elevations, as one method to evaluate parameters such as equilibrium line altitude (ELA) and mass balance of a glacier. ELA is the position, or elevation, at which accumulation is balanced by ablation. Mass balance, the difference between accumulation and ablation, is crucial to the survival of a glacier over time. Both these parameters are closely related to temperature and precipitation and can thus can serve as key indicators of climate change. We apply terrestrial glaciology inventory methods to the lobate debris aprons on the eastern rim of Hellas Basin, Mars to complete a detailed volumetric inventory of the buried ice deposits and to evaluate the hypsometric curve of each feature. We then examine the relationship between LDA hypsometry and latitude in order to understand the effect of past climatic variations on present-day ice distribution. The Thermal Emission Imaging System (THEMIS) Day IR 100m Global Mosaic was used as a base map to determine areal extent, and Mars Orbiter Laser Altimeter (MOLA) data was used to ascertain elevations. Initial results show that, at latitudes at or greater than 45°S, LDAs exhibit hypsometric curves similar to classic terrestrial alpine glaciers - that is, the curve is steep at the upper and lower boundaries, and flattens in the midsection. This type of curve is indicative of a typical glacier with both accumulation and ablation zones, and could potentially be used to determine the - probably defunct - ELA of a lobate debris apron. LDAs at latitudes closer to the equator exhibit atypical hypsometric curves. This change in hypsometry with latitude potentially signals a past shift in temperature and precipitation dependent on latitude.

Bedrock North of Terby Crater

NASA Image and Video Library

2016-06-29

This image samples the excellent bedrock exposures north of Terby Crater, which lies on the northern rim of the giant Hellas basin. An enhanced-color cutout shows a sample of this bedrock, which has a variety of colors and textures. The warm-colored bedrock probably contains hydrated minerals such as clays, whereas the blue-green bedrock is dominated by unaltered mafic minerals. These may be some of the oldest rocks exposed at the Martian surface. Such ancient rocks are extremely rare on Earth. http://photojournal.jpl.nasa.gov/catalog/PIA20737

Glacial geology of the Hellas region on Mars

NASA Technical Reports Server (NTRS)

Kargel, Jeffrey S.; Strom, Robert G.; Johnson, Natasha

1991-01-01

A glacial geologic interpretation was recently presented for Argyre, which is herein extended to Hellas. This glacial event is believed to constitute an important link in a global cryohydric epoch of Middle Amazonian age. At glacial maximum, ice apparently extended far beyond the regions of Argyre and Hellas, and formed what is termed as the Austral Ice Sheet, an agglomeration of several ice domes and lobes including the Hellas Lobe. It is concluded that Hellas was apparently heavily glaciated. Also glaciation was young by Martian standards (Middle Amazonian), and ancient by terrestrial standards. Glaciation appears to have occurred during the same period that other areas on Mars were experiencing glaciation and periglacial activity. Glaciation seems to have occurred as a geological brief epoch of intense geomorphic activity in an era characterized by long periods of relative inactivity.

Geologic Map of the MTM -30262 and -30267 Quadrangles, Hadriaca Patera Region of Mars

USGS Publications Warehouse

Crown, David A.; Greeley, Ronald

2007-01-01

Introduction Mars Transverse Mercator (MTM) -30262 and -30267 quadrangles cover the summit region and east margin of Hadriaca Patera, one of the Martian volcanoes designated highland paterae. MTM -30262 quadrangle includes volcanic deposits from Hadriaca Patera and Tyrrhena Patera (summit northeast of map area) and floor deposits associated with the Dao and Niger Valles canyon systems (south of map area). MTM -30267 quadrangle is centered on the caldera of Hadriaca Patera. The highland paterae are among the oldest, central-vent volcanoes on Mars and exhibit evidence for explosive eruptions, which make a detailed study of their geology an important component in understanding the evolution of Martian volcanism. Photogeologic mapping at 1:500,000-scale from analysis of Viking Orbiter images complements volcanological studies of Hadriaca Patera, geologic investigations of the other highland paterae, and an analysis of the styles and evolution of volcanic activity east of Hellas Planitia in the ancient, cratered highlands of Mars. This photogeologic study is an extension of regional geologic mapping east of Hellas Planitia. The Martian highland paterae are low-relief, areally extensive volcanoes exhibiting central calderas and radial channels and ridges. Four of these volcanoes, Hadriaca, Tyrrhena, Amphitrites, and Peneus Paterae, are located in the ancient cratered terrains surrounding Hellas Planitia and are thought to be located on inferred impact basin rings or related fractures. Based on analyses of Mariner 9 images, Potter (1976), Peterson (1977), and King (1978) suggested that the highland paterae were shield volcanoes formed by eruptions of fluid lavas. Later studies noted morphologic similarities between the paterae and terrestrial ash shields and the lack of primary lava flow features on the flanks of the volcanoes. The degraded appearances of Hadriaca and Tyrrhena Paterae and the apparently easily eroded materials composing their low, broad shields further suggest that the highland paterae are composed predominantly of pyroclastic deposits. Analyses of eruption and flow processes indicate that the distribution of units at Hadriaca and Tyrrhena Paterae is consistent with emplacement by gravity-driven pyroclastic flows. Detailed geologic study of the summit caldera and flanks of Hadriaca Patera is essential to determine the types of volcanic materials exposed, the nature of the processes forming these deposits, and the role of volcanism in the evolution of the cratered highlands that are characteristic of the southern hemisphere of Mars.

Dunes of the Southern Highlands

NASA Image and Video Library

2017-03-23

Sand dunes are scattered across Mars and one of the larger populations exists in the Southern hemisphere, just west of the Hellas impact basin. The Hellespontus region features numerous collections of dark, dune formations that collect both within depressions such as craters, and among "extra-crater" plains areas. This image displays the middle portion of a large dune field composed primarily of crescent-shaped "barchan" dunes. Here, the steep, sunlit side of the dune, called a slip face, indicates the down-wind side of the dune and direction of its migration. Other long, narrow linear dunes known as "seif" dunes are also here and in other locales to the east. NB: "Seif" comes from the Arabic word meaning "sword." The map is projected here at a scale of 25 centimeters (9.8 inches) per pixel. [The original image scale is 25.5 centimeters (10 inches) per pixel (with 1 x 1 binning); objects on the order of 77 centimeters (30.3 inches) across are resolved.] North is up. http://photojournal.jpl.nasa.gov/catalog/PIA21571

Albedo of the south pole on Mars determined by topographic forcing of atmosphere dynamics

USGS Publications Warehouse

Colaprete, A.; Barnes, J.R.; Haberle, R.M.; Hollingsworth, J.L.; Kieffer, H.H.; Titus, T.N.

2005-01-01

The nature of the martian south polar cap has remained enigmatic since the first spacecraft observations. In particular, the presence of a perennial carbon dioxide ice cap, the formation of a vast area of black 'slab ice' known as the Cryptic region and the asymmetric springtime retreat of the cap have eluded explanation. Here we present observations and climate modelling that indicate the south pole of Mars is characterized by two distinct regional climates that are the result of dynamical forcing by the largest southern impact basins, Argyre and Hellas. The style of surface frost deposition is controlled by these regional climates. In the cold and stormy conditions that exist poleward of 60?? S and extend 180?? in longitude west from the Mountains of Mitchel (???30?? W), surface frost accumulation is dominated by precipitation. In the opposite hemisphere, the polar atmosphere is relatively warm and clear and frost accumulation is dominated by direct vapour deposition. It is the differences in these deposition styles that determine the cap albedo.

Ripples and Dunes

NASA Image and Video Library

2006-05-27

This MOC image shows dark sand dunes on the floor of an impact crater west of Hellas Planitia. Portions of the crater floor are exposed near the center and lower right corner of the image but, in general, the floor is covered by large, windblown ripples

Crustal structure of Mars from gravity and topography

NASA Technical Reports Server (NTRS)

Neumann, G. A.; Zuber, M. T.; Wieczorek, M. A.; McGovern, P. J.; Lemoine, F. G.; Smith, D. E.

2004-01-01

Mars Orbiter Laser Altimeter (MOLA) topography and gravity models from 5 years of Mars Global Surveyor (MGS) spacecraft tracking provide a window into the structure of the Martian crust and upper mantle. We apply a finite-amplitude terrain correction assuming uniform crustal density and additional corrections for the anomalous densities of the polar caps, the major volcanos, and the hydrostatic flattening of the core. A nonlinear inversion for Moho relief yields a crustal thickness model that obeys a plausible power law and resolves features as small as 300 km wavelength. On the basis of petrological and geophysical constraints, we invoke a mantle density contrast of 600 kg m-3; with this assumption, the Isidis and Hellas gravity anomalies constrain the global mean crustal thickness to be >45 km. The crust is characterized by a degree 1 structure that is several times larger than any higher degree harmonic component, representing the geophysical manifestation of the planet's hemispheric dichotomy. It corresponds to a distinction between modal crustal thicknesses of 32 km and 58 km in the northern and southern hemispheres, respectively. The Tharsis rise and Hellas annulus represent the strongest components in the degree 2 crustal thickness structure. A uniform highland crustal thickness suggests a single mechanism for its formation, with subsequent modification by the Hellas impact, erosion, and the volcanic construction of Tharsis. The largest surviving lowland impact, Utopia, post-dated formation of the crustal dichotomy. Its crustal structure is preserved, making it unlikely that the northern crust was subsequently thinned by internal processes.

Distribution of Early, Middle, and Late Noachian cratered surfaces in the Martian highlands: Implications for resurfacing events and processes

NASA Astrophysics Data System (ADS)

Irwin, Rossman P.; Tanaka, Kenneth L.; Robbins, Stuart J.

2013-02-01

Most of the geomorphic changes on Mars occurred during the Noachian Period, when the rates of impact crater degradation and valley network incision were highest. Fluvial erosion around the Noachian/Hesperian transition is better constrained than the longer-term landscape evolution throughout the Noachian Period, when the highland intercrater geomorphic surfaces developed. We interpret highland resurfacing events and processes using a new global geologic map of Mars (at 1:20,000,000 scale), a crater data set that is complete down to 1 km in diameter, and Mars Orbiter Laser Altimeter topography. The Early Noachian highland (eNh) unit is nearly saturated with craters of 32-128 km diameter, the Middle Noachian highland (mNh) unit has a resurfacing age of ~4 Ga, and the Late Noachian highland unit (lNh) includes younger composite surfaces of basin fill and partially buried cratered terrain. These units have statistically distinct ages, and their distribution varies with elevation. The eNh unit is concentrated in the high-standing Hellas basin annulus and in highland terrain that was thinly mantled by basin ejecta near 180° longitude. The mNh unit includes most of Arabia Terra, the Argyre vicinity, highland plateau areas between eNh outcrops, and the Thaumasia range. The lNh unit mostly occurs within highland basins. Crater depth/diameter ratios do not vary strongly between the eNh and mNh units, although crater losses to Noachian resurfacing appear greater in lower lying areas. Noachian resurfacing was spatially non-uniform, long-lived, and gravity-driven, more consistent with arid-zone fluvial and aeolian erosion and volcanism than with air fall mantling or mass wasting.

Helicopter collision avoidance and brown-out recovery with HELLAS

NASA Astrophysics Data System (ADS)

Seidel, Christian; Schwartz, Ingo; Kielhorn, Peter

2008-10-01

EADS Germany is the world market leader in commercial and military Helicopter Laser Radar (HELLAS) Obstacle Warning Systems. The HELLAS-Warning System has been introduced into the market in 2000, is in service at German Federal Police and Royal Thai Air Force. HELLAS was also successfully evaluated by the Foreign Comparative Test Program (FCT) of the U.S. Army and other governmental agencies. Currently the successor system for military applications, HELLAS-Awareness, is in qualification phase. It will have extended sensor performance, enhanced real-time data processing capabilities and advanced human machine interface (HMI) features. Flight tests on NH90 helicopter have been successfully performed. Helicopter series integration is scheduled to begin from 2009. We will give an outline of the new sensor unit concerning detection technology and helicopter integration aspects. The system provides a widespread field of view with additional dynamic line of sight steering and a large detection range in combination with a high frame rate. We will show the HMI representations. This HELLAS system is the basis for a 3 dimensional see-and-remember-system for brown-out recovery. When landing in sandy or dusty areas the downwash of the helicopter rotor causes clouds of visually-restrictive material that can completely obstruct the pilot's outside reference, resulting in a complete loss of situational awareness and spatial orientation of the pilot which can end up in total loss of aircraft control and dangerous accidents. The brown-out recovery system presented here creates an augmented enhanced synthetic vision of the landing area with the surrounding which is based on HELLAS range image data as well as altimeter and inertial reference information.

Glaciation at the Eastern Hellas Margin

NASA Image and Video Library

2014-08-13

Hellas Crater in the ancient highlands contains some of the clearest evidence on Mars for glacial processes. This image from NASA Mars Reconnaissance Orbiter shows a number of features consistent with glaciation.

Noachian Climate of Mars: Insights from Noachian Stratigraphy and Valley Networks System Formation Times

NASA Astrophysics Data System (ADS)

Head, J. W., III

2017-12-01

Noachian climate models have been proposed in order to account for 1) observed fluvial and lacustrine activity, 2) weathering processes producing phyllosilicates, and 3) an unusual impact record including three major impact basins and unusual degradation processes. We adopt a stratigraphic approach in order place these observations in a temporal context. Formation of the major impact basins Hellas, Isidis and Argyre in earlier Noachian profoundly influenced the uplands geology and appears to have occurred concurrently with major phyllosilicate and related surface occurrences/deposits; the immediate aftermath of these basins appears to have created a temporary hot and wet surface environment with significant effect on surface morphology and alteration processes. Formation of Late Noachian-Early Hesperian valley network systems (VNS) signaled the presence of warm/wet conditions generating several hypotheses for climates permissive of these conditions. We examined estimates for the time required to carve channels/deltas and total duration implied by plausible intermittencies. Synthesis of required timescales show that the total time to carve the VN does not exceed 106 years, < 0.25% of the total Noachian. What climate models can account for the VNS? 1) Warm and wet/semiarid/arid climate: Sustained background MAT >273 K, hydrological system vertically integrated, and rainfall occurs to recharge the aquifer. 2) Cold and Icy climate warmed by greenhouse gases or episodic stochastic events: Climate is sustained cold/icy, but greenhouse gases of unspecified nature/amount/duration elevate MAT by several tens of Kelvins, bringing the annual temperature range into the realm where peak seasonal temperatures (PST) exceed 273 K. In this climate environment, analogous to the Antarctic Dry Valleys, seasonal summer temperatures above 273 K are sufficient to melt snow/ice and form fluvial and lacustrine features, but MAT is well below 273 K (253 K); punctuated warming alternatives include impacts or volcanic eruptions. We conclude that a cold and icy background climate with modest greenhouse warming or punctuated warming and melting events for the VNs origin is consistent with: 1) the estimated durations of continuous VN formation (<105 years) and 2) VN system estimated recurrence rates (106-107 years).

Stickney Crater on Phobos and some other outstanding planetary depressions as features of crustal wave interference origin

NASA Astrophysics Data System (ADS)

Kochemasov, G. G.

2011-10-01

Some not fully understood (enigmatic) large planetary depressions and geoid minima on planets and satellites are better understood as regular wave woven features, not random large impacts [1]. A main reason for this is their similar tectonic position in a regular sectoral network produced by interfering crossing standing waves warping any celestial body. These waves arise in the bodies due to their movements in keplerian elliptical orbits with changing accelerations. The fundamental wave1 produces universal tectonic dichotomy, its first overtone wave2 superposes on it sectoring - a regular network of risen and fallen blocks [2, 3]. Thus, deeply subsided sectoral blocks are formed on uplifted highland segments -hemispheres [1]. Examples of this pattern are shown in Fig. 1 to 8 on various globes and irregular bodies. The Moon - the SPA basin, Earth - Indian geoid min imum, Phobos - Stickney Crater, Miranda - an ovoid, Phoebe - a sector, Mars - Hellas Planitia, Lutetia - a deep sector indentation. Fig. 9 - a geometrical model of dichotomy and sectors format ion by wave interference.

Giant Icebergs and Biological Productivity on Early Mars

NASA Astrophysics Data System (ADS)

Uceda, E.; Fairen, A. G.; Woodworth-Lynas, C.

2016-12-01

We have previously presented evidence for furrows, dump structures and chains of craters that we interpret as indication for giant iceberg transport and grounding on very cold oceans on early Mars, both in the northern plains and in the Hellas basin. Structures include: 1. Furrows: The furrows are located in elevated areas or on local topographic highs, particularly on the Hellas basin. We interpret these features in terms of iceberg rafting and grounding. 2. Chains of craters: High-resolution images of Utopia and Isidis Basins reveal chains of crater-like structures several hundred meters wide and 1 to 5 km long. 3. Dump structures: Dark boulder clusters are revealed at large scales by their slightly darker tonality with respect to the surrounding terrain. These clusters have sizes ranging from several hundred meters to 1-2 km. On Earth's oceans, giant icebergs release melting water containing nanoparticulate iron and other micronutrients, which support biological metabolism and growth to the near-coastal euphotic ecosystems, many of which are iron limited. This iron limitation of primary producers has been documented in large regions of the Earth's oceans, most notably in polar areas proximal to significant glacial activity, and is counterbalanced by the substantial enrichment of terrigenous material supplied by icebergs. The biological productivity extends hundreds of kilometres from the giant icebergs, and persists for over one month after the iceberg passes. Here we propose that giant iceberg activity on early Mars could have promoted a similar enhancing of biological productivity on the planet's oceans. The identification of specific biosignatures in icebergs trails on Earth could give clues as to what kind of biosignatures could be expected on the ancient Mars ocean floors, and where to look for them. In particular, assuming that life existed on Mars coeval to glacial activity, enhanced concentrations of organic carbon could be anticipated near giant iceberg trails, analogous to what is observed in polar oceans on Earth. Acknowledgements: The research leading to these results is a contribution from the Project "icyMARS", funded by the European Research Council, Starting Grant no 307496.

Modification history of the Harmakhis Vallis outflow channel, Mars, based on CTX-scale photogeologic mapping and crater count dating

NASA Astrophysics Data System (ADS)

Kukkonen, S.; Kostama, V.-P.

2018-01-01

Harmakhis Vallis is one of the four major outflow channel systems (Dao, Niger, Harmakhis, and Reull Valles) that cut the eastern rim region of the Hellas basin, the largest well-preserved impact structure on Mars. The structure of Harmakhis Vallis and the volume of its head depression, as well as earlier dating studies of the region, suggest that the outflow channel formed in the Hesperian period by collapsing when a large amount of subsurface fluid was released. Thus Harmakhis Vallis, as well as the other nearby outflow channels, represents a significant stage of the fluvial activity in the regional history. On the other hand, the outflow channel lies in the Martian mid-latitude zone, where there are several geomorphologic indicators of past and possibly also contemporary ground ice. The floor of Harmakhis also displays evidence of a later-stage ice-related activity, as the outflow channel has been covered by lineated valley fill deposits and debris apron material. The eastern rim region of the Hellas impact basin has been the subject of numerous geologic mapping studies at various scales and based on different imaging data sets. However, Harmakhis Vallis itself has received less attention and the studies on the outflow channel have focused only on limited parts of the outflow channel or on separated different geologic events. In this work, the Harmakhis Vallis floor is mapped and dated from the head depression to the beginning of the terminus based on the Mars Reconnaissance Orbiter's ConTeXt camera images (CTX; ∼ 6 m/pixel). Our results show that Harmakhis Vallis has been modified by several processes after its formation. Age determinations on the small uncovered parts of the outflow channel, which possibly represent the original floor of Harmakhis, imply that Harmakhis may have experienced fluvial activity only 780-850 ( ± 400-600) Ma ago. The discovered terrace structure instead shows that the on-surface activity of the outflow channel has been periodic. The most significant of the modification processes on Harmakhis Vallis has been the formation of lineated valley fill units. The lineated valley fills now cover the outflow channel almost entirely. They formed not later than ∼ 400 Ma ago based on stratigraphic analyses and crater counts. All the floor units have also been resurfaced several, usually two or three times. The resurfacing ages of the dated units show that the later modification processes have occurred at least on a local scale in the Harmakhis Vallis region, not only inside the outflow channel. This, in turn, may indicate that the processes resulted from a larger-scale change, for example in the local climate or endogenic conditions.

Use of spacecraft data to derive regions on Mars where liquid water would be stable

PubMed Central

Lobitz, Brad; Wood, Byron L.; Averner, Maurice M.; McKay, Christopher P.

2001-01-01

Combining Viking pressure and temperature data with Mars Orbital Laser Altimeter topography data, we have computed the fraction of the martian year during which pressure and temperature allow for liquid water to be stable on the martian surface. We find that liquid water would be stable within the Hellas and Argyre basin and over the northern lowlands equatorward of about 40°. The location with the maximum period of stable conditions for liquid water is in the southeastern portion of Utopia Planitia, where 34% of the year liquid water would be stable if it were present. Locations of stability appear to correlate with the distribution of valley networks. PMID:11226204

Use of Spacecraft Data to Drive Regions on Mars where Liquid Water would be Stable

NASA Technical Reports Server (NTRS)

Lobitz, Brad; Wood, Byron L.; Averner, Maurice M.; McKay, Christopher P.; MacElroy, Robert D.

2001-01-01

Combining Viking pressure and temperature data with Mars Orbital Laser Altimeter (MOLA) topography data we have computed the fraction of the martian year during which pressure and temperature allow for liquid water to be stable on the martian surface. We find that liquid water would be stable within the Hellas and Argyre basin and over the northern lowlands equatorward of about 40 degrees. The location with the maximum period of stable conditions for liquid water is in the southeastern portion of Utopia Planitia where 34% of the year liquid water would be stable if it was present. Locations of stability appear to correlate with the distribution of valley networks.

Internal Structure of a Lobate Debris Apron Complex in Eastern Hellas: Evidence for Multiple Mid-Latitude Glaciations on Mars

NASA Astrophysics Data System (ADS)

Quartini, E.; Holt, J. W.; Brothers, T. C.

2011-03-01

The past depositional history of a lobate debris apron complex in eastern Hellas has been investigated by conducting a combined analysis of its surface morphology and subsurface structure using a CTX mosaic and orbital radar sounding data from SHARAD.

Arecibo radar imagery of Mars: II. Chryse-Xanthe, polar caps, and other regions

NASA Astrophysics Data System (ADS)

Harmon, John K.; Nolan, Michael C.

2017-01-01

We conclude our radar imaging survey of Mars, which maps spatial variations in depolarized radar reflectivity using Arecibo S-band (λ12.6 cm) observations from 2005-2012. Whereas our earlier paper (Harmon et al., 2012, Arecibo radar imagery of Mars: the major volcanic provinces. Icarus 220, 990-1030) covered the volcanic regions of Tharsis, Elysium, and Amazonis, this paper includes non-volcanic regions where hydrologic and impact processes can be the dominant resurfacing agents affecting radar backscatter. Many of the more prominent and interesting radar-bright features outside the major volcanic provinces are located in and around Chryse Planitia and Xanthe Terra. These features are identified with: a basin in northeast Lunae Planum containing the combined deposits from Maja Vallis and Ganges Catena outflows; channel outwash plains in western and southern Chryse basin; plateaus bordering chasma/chaos zones, where surface modification may have resulted from hydrologic action associated with incipient chaos formation; and some bright-ejecta craters in Chryse basin, of a type otherwise rare on Mars. Dark-halo craters have also been identified in Chryse and elsewhere that are similar to those seen in the volcanic provinces. Although the cratered highlands are relatively radar-bland, they do exhibit some bright depolarized features; these include eroded crater rims, several unusual ejecta flows and impact melts, and terrain-softened plains. The rims of large impact basins (Hellas, Argyre, Isidis) show a variety of radar-bright features provisionally identified with massif slopes, erosion sediments, eroded pyroclastics, impact melts, and glacial deposits. The interiors of these basins are largely radar-dark, which is consistent with coverage by rock-free sediments. Tempe Terra and Acheron Fossae show bright features possibly associated with rift volcanism or eroded tectonic structures, and northwest Tempe Terra shows one very bright feature associated with glacial or other ice processes in the dichotomy boundary region. The first delay-Doppler images of the radar-bright features from the north and south polar icecaps are presented. Both poles show the circular polarization inversion and high reflectivity characteristic of coherent volume backscatter from relatively clean ice. The south polar feature is primarily backscatter from the residual CO2 icecap (with a lesser contribution from the polar layered deposits), whose finite optical depth probably accounts for the feature's strong S/X-band wavelength dependence. Conversely, the north polar radar feature appears to be mostly backscatter from the H2O-ice-rich polar layered deposits rather than from the thin residual H2O cap. The north polar region shows additional radar-bright features from Korolev Crater and a few other outlying circumpolar ice deposits.

Schiaparelli Hemisphere

NASA Image and Video Library

1996-06-03

This mosaic is composed of about 100 red- and violet- filter Viking Orbiter images, digitally mosaiced in an orthographic projection at a scale of 1 km/pixel. The images were acquired in 1980 during mid northern summer on Mars (Ls = 89 degrees). The center of the image is near the impact crater Schiaparelli (latitude -3 degrees, longitude 343 degrees). The limits of this mosaic are approximately latitude -60 to 60 degrees and longitude 280 to 30 degrees. The color variations have been enhanced by a factor of two, and the large-scale brightness variations (mostly due to sun-angle variations) have been normalized by large-scale filtering. The large circular area with a bright yellow color (in this rendition) is known as Arabia. The boundary between the ancient, heavily-cratered southern highlands and the younger northern plains occurs far to the north (latitude 40 degrees) on this side of the planet, just north of Arabia. The dark streaks with bright margins emanating from craters in the Oxia Palus region (to the left of Arabia) are caused by erosion and/or deposition by the wind. The dark blue area on the far right, called Syrtis Major Planum, is a low-relief volcanic shield of probable basaltic composition. Bright white areas to the south, including the Hellas impact basin at the lower right, are covered by carbon dioxide frost. http://photojournal.jpl.nasa.gov/catalog/PIA00004

The effect of giant impactors on the magnetic field energy of an early Martian dynamo.

NASA Astrophysics Data System (ADS)

Drummond, McGregor; Thieulot, Cedric; Monteux, Julien

2016-04-01

Through the cratering record embedded on its surface, Mars is one of the key planets required for investigating the formation and impact frequency in the early history of our Solar System. This record also holds clues to the events that may have caused the observed hemispheric dichotomy and cessation of the magnetic field that was present within the first 500 Myr of the planets' formation. We investigate the influence of giant impacts on the early Martian dynamo using the numerical dynamo modelling code PARODY-JA [1]. We hypothesize that the input heat from a giant impact will decrease the total heat flux at the CMB through mantle heating which leads to a decrease in the Rayleigh number of the core. As boundary conditions for the heat flux anomaly size, we use numerical results of a 750 km diameter impactor from the Monteux and Arkani-Hamed, 2014 [2] study which investigated impact heating and core merging of giant impacts in early Mars. We also determine the decrease in Rayleigh number from the change in total heat flux at the CMB using these results, where the decrease after impact is due to shock heating at the CMB. We calculate the time-averaged total magnetic field energy for an initial homogeneous heat flux model using a range of Rayleigh numbers (5 x 103 - 1 x 10^5). The Rayleigh number is then decreased for three new models - homogeneous, north pole impact and equatorial impact - and the time-averaged energy again determined. We find that the energy decreases more in our impact models, compared with the homogeneous, along with a variation in energy between the north pole and equatorial impact models. We conclude that giant impacts in Mars' early history would have decreased the total magnetic energy of the field and the decrease in energy is also dependent on the location of the impact. The magnetic field could have been disrupted beyond recovery from a planetesimal-sized collision; such as the suggested Borealis basin forming impact, or through the cumulative effect of multiple large impactors; such as Utopia, Hellas and Isidis basin forming impacts. [1] Aubert, J., Aurnou, J. & Wicht, J., 2008. The magnetic structure of convection-driven numerical dynamos. Geophys. J. Int., 172, 945--956. [2] Monteux, J., Arkani-Hamed, J., 2014. Consequences of giant impacts in early Mars: core merging and Martian dynamo evolution. J. Geophys. Res. (Planets) 119, 480--505.

Mars At Opposition

NASA Technical Reports Server (NTRS)

1995-01-01

These NASA Hubble Space Telescope views provide the most detailed complete global coverage of the red planet Mars ever seen from Earth. The pictures were taken on February 25, 1995, when Mars was at a distance of 65 million miles (103 million km).

To the surprise of researchers, Mars is cloudier than seen in previous years. This means the planet is cooler and drier, because water vapor in the atmosphere freezes out to form ice-crystal clouds. Hubble resolves Martian surface features with a level of detail only exceeded by planetary probes, such as impact craters and other features as small as 30 miles (50 kilometers) across.

[Tharsis region] - A crescent-shaped cloud just right of center identifies the immense shield volcano Olympus Mons, which is 340 miles (550 km) across at its base. Warm afternoon air pushed up over the summit forms ice-crystal clouds downwind from the volcano. Farther to the east (right) a line of clouds forms over a row of three extinct volcanoes which are from north to south: Ascraeus Mons, Pavonis Mons, Arsia Mons. It's part of an unusual, recurring 'W'-shaped cloud formation that once mystified earlier ground-based observers.

[Valles Marineris region] - The 16 mile-high volcano Ascraeus Mons pokes through the cloud deck along the western (left) limb of the planet. Other interesting geologic features include (lower left) Valles Marineris, an immense rift valley the length of the continental United States. Near the image center lies the Chryse basin made up of cratered and chaotic terrain. The oval-looking Argyre impact basin (bottom) appears white due to clouds or frost.

[Syrtis Major region] - The dark 'shark fin' feature left of center is Syrtis Major. Below it the giant impact basin Hellas. Clouds cover several great volcanos in the Elysium region near the eastern (right) limb. As clearly seen in the Hubble images, past dust storms in Mars' southern hemisphere have scoured the plains of fine light dust and transported the dust northward. This leaves behind a relatively coarser, and less reflective sand in, predominantly, the southern hemisphere.

The pictures were taken with Hubble's Wide Field Planetary Camera 2.

This image and other images and data received from the Hubble Space Telescope are posted on the World Wide Web on the Space Telescope Science Institute home page at URL http:// oposite.stsci.edu/pubinfo/

Polygon/Cracked Sedimentary Rock

NASA Technical Reports Server (NTRS)

2004-01-01

4 December 2004 Exposures of sedimentary rock are quite common on the surface of Mars. Less common, but found in many craters in the regions north and northwest of the giant basin, Hellas, are sedimentary rocks with distinct polygonal cracks in them. This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows an example from the floor of an unnamed crater near 21.0oS, 311.9oW. Such cracks might have formed by desiccation as an ancient lake dried up, or they might be related to ground ice freeze/thaw cycles or some other stresses placed on the original sediment or the rock after it became lithified. The 300 meter scale bar is about 328 yards long. The scene is illuminated by sunlight from the upper left.

Looking for water related environments on Mars: analysis of reflectance spectra for present and future exploration

NASA Astrophysics Data System (ADS)

De Toffoli, B.; Carli, C.; Maturilli, A.; Sauro, F.; Massironi, M.; Helbert, J.

2017-09-01

Spectroscopic analyses of basalt epithermal alterations, clay minerals and samples representative of wet sedimentary environments in a broad wavelength range from the ultraviolet to the far-infrared provide new loads of information for present and future exploration of environments that could have been linked to water and gas emission. Specifically, methane emission centers on the Martian surface are high interest targets for Exo-Mars mission since they involve environments where life could have potentially arisen, grown and given a contribution to the degassing phenomenon. Such data will be applied to drive the analysis on remotely sensed hyperspectral images of Martian regions where surface expressions of water and sediments resurgences are recognisable, such as the mound fields detected in Utopia and Hellas basins and Vastitas Borealis.

Geologic Mapping of MTM -30247, -35247 and -40247 Quadrangles, Reull Vallis Region, Mars

NASA Technical Reports Server (NTRS)

Mest, S. C.; Crown, D. A.

2009-01-01

Geologic mapping of MTM -30247, -35247, and -40247 quadrangles is being used to characterize Reull Vallis (RV) and to determine the history of the eastern Hellas region of Mars. Studies of RV examine the roles and timing of volatile-driven erosional and depositional processes and provide constraints on potential associated climatic changes. This study complements earlier investigations of the eastern Hellas region, including regional analyses [1-6], mapping studies of circum-Hellas canyons [7-10], and volcanic studies of Hadriaca and Tyrrhena Paterae [11-13]. Key scientific objectives include 1) characterizing RV in its "fluvial zone," 2) analysis of channels in the surrounding plains and potential connections to and interactions with RV, 3) examining young, presumably sedimentary plains along RV, and 4) determining the nature of the connection between the segments of RV.

Channel geometry and discharge estimates for Dao and Niger Valles, Mars

NASA Astrophysics Data System (ADS)

Musiol, S.; van Gasselt, S.; Neukum, G.

2008-09-01

Introduction The outflow channels Dao and Niger Valles are located at the eastern rim of the 2000-km diameter Hellas Planitia impact basin, in a transition zone with ancient cratered terrain and the volcanoes Hadriaca and Tyrrhena Patera (Hesperia Planum) on the one hand and fluvial, mass-wasting and aeolian deposits on the other hand [1]. Dao and Niger have alcove-shaped source regions similar to the chaotic terrains found in the Margaritifer Terra region, with flat floors, landslide morphologies and small, chaotically distributed isolated mounds. As [2] pointed out, the intrusion of volcanic material could be responsible for the release of pressurized water that can carry loose material away. This process could than have created a depression and an associated outflow channel. In contrast to [2] who made their calculations for Aromatum Chaos and Ravi Vallis, we have focused on Dao and Niger Valles for investigation, since they are spatially related to the nearby Hadriaca Patera. Heat-triggered outflow events seem likely. We follow the generally accepted assumption that water was the main erosional agent [3]. Furthermore we take into account that multiple floods with different volumes are more likely than a single event because of repressurization of an aquifer [4]. Background Hadriaca Patera Hadriaca Patera is among the oldest central-vent volcanoes on Mars, a low-relief volcano with a central caldera complex which consists predominantly of pyroclastic material. The erosional structure of degraded valleys on its flanks is indicative of dissection by a combination of groundwater sapping and surface runoff, attributed to a hydromagmatic eruption scenario [5]. Dao Vallis Dao Vallis is interpreted as collapse region of volcanic and sedimentary plains that have been eroded by surface and subsurface flow [5]. The approximately radial alignment to Hellas is interpreted as following deep-seated structural weakness zones generated by the impact. Small grabens and fractures parallel to the channel margins are considered to be the result of extensional deformation. Two smoothfloored collapse depressions, representing source areas, cut into the flanks of Hadriaca Patera (Ausonia and Peraea Cavus) and are connected to Dao Vallis by a region of irregular valley floor materials. These regions are all bounded by steep scarps and are interpreted to be collapse depressions in water- or ice-rich materials. Linear and curvilinear features that are approximately parallel to the channel walls are seen in some parts of the channel floors. The channel walls show typical spur-and-gully morphology. It has been suggested that gullies can be exposed by a removal of semi-competent mantling deposits along the walls of Dao Vallis. The walls could either be a source of volatiles or provide an insulating layer [6]. A possible sedimentary deposit is observed on the floor of Hellas near the terminus of Dao Vallis [1]. Geologic evolution of the eastern rim of Hellas The oldest geologic materials result from the basin-forming impact and consist of the Noachian basin rim unit and mountainous materials. Volcanism began in the late Noachian or Early Hesperian epoch with the formation of the highland paterae. The low shields of Hadriaca and Tyrrhena Patera are interpreted to be composed primarily of pyroclastic flows. The distribution of flank materials at Hadriaca Patera can be attributed to the emplacement of gravity-driven pyroclastic flow, which is in contrast to the caldera-filling material and implies a transition from explosive to effusive volcanism at the highland paterae [5]. Substantial modification of the cratered highlands characterizes the Hesperian Period, with the formation of the smooth plateau materials, predominantly sedimentary plains-infilling low-lying intermontane areas. Continuation of this style of erosion extended into the Amazonian Period with the emplacement of debris aprons. The channels on the flanks of Hadriaca Patera are clearly truncated by Dao Vallis and appear to be truncated by the channeled plains, indicating that the erosion of Hadriaca Patera preceded erosion on the plains [1]. Data sets and additional information For the eastern-Hellas region a sufficient HRSC coverage exists. In addition, age estimates for the channel floors and the surrounding plains are available [7]. For detailed studies we processed MOC and HIRISE images also. Moreover, a detailed geologic map of the Hellas region has been made [8] which was utilized to constrain the channel boundaries and the main branches. Computations are actually done with MOLA data, but will be further improved by a high resolution mosaic DTM created out of HRSC stereo data of the eastern Hellas area. Water flow experiments within a Mars Simulation Chamber conducted at the Open University London, Department of Earth and Environmental Sciences (pers. comm.), suggest a complex interaction of phase changes (boiling and freezing) which have to be kept in mind when modeling the discharge of water from the subsurface. Such experiments will be improved in further investigations to give a better input to numerical modeling. Work plan The objective of the ongoing work is to make a quantitative comparison between the amount of water that could be melted by volcano-permafrost interaction and the outflow volume derived from channel and chaotic terrain morphology. The melted water is supposed to be initially stored as ice in a subsurface porous medium, so that the quested volume depends on the pore space and drainage area to be reached by a heat supplier. To find an approach to this problem, we want to reconstruct the outflow event by computing the discharge and sediment transport rate for Dao and Niger Valles under consideration of flow and transport processes in martian channels reviewed by [9]. The theoretical background of this work is used to derive model parameters. Channel width and water depth were obtained using individual MOLA tracks. Together with an assumed flow velocity based upon energy slope of the flow we calculate the discharge. Unlike previous calculations we will use the nondimensionalized Darcy- Weisbach equation for depth- and width-averaged flow velocity which has a depth-dependent roughness coefficient [9]. In order to investigate the history of the channel genesis we need a timescale, which can be derived from the discharge and volume of the removed material. Rather than utilizing individual MOLA profiles we base our estimates of channel dimensions on high-resolution DTM data obtained from HRSC stereo information. This process includes determination of overall volume by digitizing the channel area, creating TIN (triangulated irregular network) elements with individual height values (rather than assuming a flat cover) in order to obtain the surface before channel formation. The overall volume of removed material can be derived from height differences in combination with cellsize. Our first results show that a volume of 11400 km3 has been removed from the Dao source region. This can be compared to the volumes computed for some chaos regions as cited by [10]: Iani Chaos 32000 km3, Aram Chaos 28000 km3 and Margaritifer Chaos 23000 km3. These were determined from a combination of shadow and stereo measurements. The volume for Dao will be much better constrained. Further work, based on the conditions on the surface of Mars today, will include the significant but still open question of water phase changes and the timescale of these processes, compared to the derived timescale for the channel formation. References [1] Crown, D. A. et al. (1992) Icarus, 100, 1-25. [2] Leask, H. J. et al. (2006) JGR, 111, E08071. [3] Coleman, N. M. (2003), JGR, 108, E5-1-E5-15. [4] Andrews-Hanna, J. C. and Phillips, R. J. (2007) JGR, 112, E08001. [5] Crown, D. A. and Greeley, R. (1993) JGR, 98, 3431- 3451. [6] Bleamaster, L. F. III and Crown, D. A. (2005) GRL, 32, L20203. [7] Zuschneid, W. et al. (2005) EGU05-A-08664 / Zuschneid, W. (2005) diploma thesis FU Berlin. [8] Leonard, G. J. and Tanaka, K. L. (2001) Geol. Invest. Ser. I-2694. [9] Kleinhans, M. G. (2005) JGR, 110, E12003. [10] Carr, M. H. (1996) Oxford University Press. Acknowledgements This work has been supported financially by the German Space Agency (DLR Bonn).

Smooth and Fractured Deposits in Eridania Valleys

NASA Image and Video Library

2017-01-13

The ancient highland channels in this image empty into the Eridania Basin (not visible), a large topographically low enclosure with smooth-appearing terrains that may have once contained a large paleolake or ancient sea. Water in these channels flowed to the east into Ariadnes Basin, a smaller basin located within the confines of Eridiana. Light-toned knobs are exposed in the northern channel, while the other channels are partially filled with smooth appearing lobe-shaped surface flows that are extensively fractured when viewed at high-resolution. Although the origin of these knobs is not known, interpretations include fumarolic mounds, erosional remnants, pingos, mud volcanoes and spring mounds. The movement of the once ice-rich, channel-filling flows over the knobby terrains likely created radial tension stresses producing the cracks that we see on the surface of these deposits. As the material slowly thinned, it eventually led to the formation of an elephant skin-like texture. This texture is different from the surrounding eroding mantling deposit that has become pitted as the ice sublimated causing the overlying surface to collapse. The combination of such knobby terrain and smooth, channel-filling deposits are seen only in a few places on Mars. One such example is the Navua Valles channels northeast of the Hellas Basin that may have also hosted a large, ice-covered lake in the past. Their morphological similarities, particularly in their surface materials, suggest that they formed under similar paleoclimatic conditions. http://photojournal.jpl.nasa.gov/catalog/PIA12968

Geologic Mapping of MTM -30247, -35247 and -40247 Quadrangles, Reull Vallis Region of Mars

NASA Technical Reports Server (NTRS)

Mest, S. C.; Crown, D. A.

2008-01-01

Geologic mapping and stratigraphic analyses of MTM -30247, -35247, and -40247 quadrangles are being used to characterize the Reull Vallis (RV) system and to determine the history of the eastern Hellas region of Mars. Studies of RV examine the roles and timing of volatile-driven erosional and depositional processes and provide constraints on potential associated climatic changes. This study complements earlier investigations of the eastern Hellas region, including regional analyses [1-6], mapping studies of circum-Hellas canyons [7-10], and volcanic studies of Hadriaca and Tyrrhena Paterae [11-13]. Key scientific objectives for these quadrangles include 1) characterization of RV in its "fluvial zone," 2) analysis of channels in the surrounding plains and potential connections to and interactions with RV, 3) examination of young (?), presumably sedimentary plains along RV that embay the surrounding highlands, and 4) determination of the nature of the connection between segments 1 and 2 of RV.

Application of Geographical Information System Arc/info Grid-Based Surface Hyrologic Modeling to the Eastern Hellas Region, Mars

NASA Astrophysics Data System (ADS)

Mest, S. C.; Harbert, W.; Crown, D. A.

2001-05-01

Geographical Information System GRID-based raster modeling of surface water runoff in the eastern Hellas region of Mars has been completed. We utilized the 0.0625 by 0.0625 degree topographic map of Mars collected by the Mars Global Surveyor Mars Orbiter Laser Altimeter (MOLA) instrument to model watershed and surface runoff drainage systems. Scientific interpretation of these models with respect to ongoing geological mapping is presented in Mest et al., (2001). After importing a region of approximately 77,000,000 square kilometers into Arc/Info 8.0.2 we reprojected this digital elevation model (DEM) from a Mars sphere into a Mars ellipsoid. Using a simple cylindrical geographic projection and horizontal spatial units of decimal degrees and then an Albers projection with horizontal spatial units of meters, we completed basic hydrological modeling. Analysis of the raw DEM to determine slope, aspect, flow direction, watershed and flow accumulation grids demonstrated the need for correction of single pixel sink anomalies. After analysis of zonal elevation statistics associated with single pixel sinks, which identified 0.8 percent of the DEM points as having undefined surface water flow directions, we filled single pixel sink values of 89 meters or less. This correction is comparable with terrestrial DEMs that contain 0.9 percent to 4.7 percent of cells, which are sinks (Tarboton et al., 1991). The fill-corrected DEM was then used to determine slope, aspect, surface water flow direction and surface water flow accumulation. Within the region of interest 8,776 watersheds were identified. Using Arc/Info GRID flow direction and flow accumulation tools, regions of potential surface water flow accumulation were identified. These networks were then converted to a Strahler ordered stream network. Surface modeling produced Strahler orders one through six. As presented in Mest et al., (2001) comparisons of mapped features may prove compatible with drainage networks and watersheds derived using this methodology. Mest, Scott C., Crown, David A., and Harbert, William, 2001, Highland drainage basins and valley networks in the eastern Hellas Region of Mars, Abstract 1419, Lunar and Planetary Science XXXII Meeting Houston (CDROM). Tarboton D. G., Bras, R. L., and Rodriguez-Iturbe, 1991, On the Extraction of Channel Networks from Digital Elevation Data, Hydrological Processes, v. 5, 81-100. http://viking.eps.pitt.edu

Comprehensive amateur coverage of the Mars 2015-2017 apparition from the Southern Hemisphere

NASA Astrophysics Data System (ADS)

Foster, C.

2017-09-01

Although there are current, active scientific assets orbiting and on the surface of Mars, comprehensive amateur monitoring of the planet can still add value. With latest technology and improved high resolution imaging techniques, amateurs are still in a position to observe and report in real time on any significant atmospheric activity on the planet. The author was able to follow the 2015-2017 Mars apparition comprehensively from December 2015 through until February 2017. The planet was imaged on 198 nights by the author during this period, and although no major(non-regional) dust storms occurred during the apparition, a number of atmospheric phenomena were noted and imaged. Orographic cloud formations, Northern and southern polar hood development, high latitude weather systems and the changing weather systems and conditions in and around the Hellas basin were observed and recorded.

Abstracts of the Annual Meeting of Planetary Geologic Mappers, San Antonio, TX, 2009

NASA Technical Reports Server (NTRS)

Bleamaster, Leslie F., III (Editor); Tanaka, Kenneth L.; Kelley, Michael S.

2009-01-01

Topics covered include: Geologic Mapping of the Beta-Atla-Themis (BAT) Region of Venus: A Progress Report; Geologic Map of the Snegurochka Planitia Quadrangle (V-1): Implications for Tectonic and Volcanic History of the North Polar Region of Venus; Preliminary Geological Map of the Fortuna Tessera (V-2) Quadrangle, Venus; Geological Map of the Fredegonde (V-57) Quadrangle, Venus; Geological Mapping of the Lada Terra (V-56) Quadrangle, Venus; Geologic Mapping of V-19; Lunar Geologic Mapping: A Preliminary Map of a Portion of the LQ-10 ("Marius") Quadrangle; Geologic Mapping of the Lunar South Pole, Quadrangle LQ-30: Volcanic History and Stratigraphy of Schr dinger Basin; Geologic Mapping along the Arabia Terra Dichotomy Boundary: Mawrth Vallis and Nili Fossae, Mars; Geologic Mapping Investigations of the Northwest Rim of Hellas Basin, Mars; Geologic Mapping of the Meridiani Region of Mars; Geology of a Portion of the Martian Highlands: MTMs -20002, -20007, -25002 and -25007; Geologic Mapping of Holden Crater and the Uzboi-Ladon-Morava Outflow System; Mapping Tyrrhena Patera and Hesperia Planum, Mars; Geologic Mapping of Athabaca Valles; Geologic Mapping of MTM -30247, -35247 and -40247 Quadrangles, Reull Vallis Region, Mars Topography of the Martian Impact Crater Tooting; Mars Structural and Stratigraphic Mapping along the Coprates Rise; Geology of Libya Montes and the Interbasin Plains of Northern Tyrrhena Terra, Mars: Project Introduction and First Year Work Plan; Geology of the Southern Utopia Planitia Highland-Lowland Boundary Plain: Second Year Results and Third Year Plan; Mars Global Geologic Mapping: About Half Way Done; New Geologic Map of the Scandia Region of Mars; Geologic Mapping of the Medusae Fossae Formation on Mars and the Northern Lowland Plains of Venus; Volcanism on Io: Insights from Global Geologic Mapping; and Planetary Geologic Mapping Handbook - 2009.

Volcanic flows versus water- and ice-related outburst deposits in eastern Hellas: A comparison

NASA Astrophysics Data System (ADS)

Voelker, M.; Hauber, E.; Stephan, K.; Jaumann, R.

2018-06-01

Hellas Planitia is one of the major topographic sinks on Mars for the deposition of any kind of sediments. We report on our observations of sheet deposits in the eastern part of the basin that are apparently related to the Dao Vallis outflow channel. The deposits have lobate flow fronts and a thickness of a few decameters. Despite their generally smooth surface, some distinctive textures and patterns can be identified, such as longitudinal lineations, distributive channels, and polygons. We compared these deposits to other sheet deposits on Mars and tested three hypotheses of their origin: volcanic flows as well as water- and ice-related mass wastings. Despite some similarities to volcanic sheet flows on Mars, we found several morphological characteristics that are not known for sheet lava flows; for example conically arranged lineations and channel systems very similar to fluvial incisions. We also reject an ice-related formation similar to terrestrial rock-ice avalanches, as there is no sufficient relief energy to explain their extent and location. A water-related origin appears most consistent with our observations, and we favor an emplacement by fluvially-driven mass wasting processes, e.g., debris flows. Assuming a water-related origin, we calculated the amount of water that would be required to deposit such large sedimentary bodies for different flow types. Our calculations show a large range of possible water volumes, from 64 to 2,042 km³, depending on the specific flow mechanism. The close link to Dao Vallis makes these deposits a unique place to study the deposition of outflow channel sediments, as the deposits of other outflow channels on Mars, such as those around Chryse Planitia, are mostly buried by younger sediments and volcanic flows.

Discovery of columnar jointing on Mars

USGS Publications Warehouse

Milazzo, M.P.; Keszthelyi, L.P.; Jaeger, W.L.; Rosiek, M.; Mattson, S.; Verba, C.; Beyer, R.A.; Geissler, P.E.; McEwen, A.S.

2009-01-01

We report on the discovery of columnar jointing in Marte Valles, Mars. These columnar lavas were discovered in the wall of a pristine, 16-km-diameter impact crater and exhibit the features of terrestrial columnar basalts. There are discontinuous outcrops along the entire crater wall, suggesting that the columnar rocks covered a surface area of at least 200 km2, assuming that the rocks obliterated by the impact event were similarly jointed. We also see columns in the walls of other fresh craters in the nearby volcanic plains of Elysium Planitia-Amazonis Planitia, which include Marte Vallis, and in a well-preserved crater in northeast Hellas. ?? 2009 The Geological Society of America.

The discovery of columnar jointing on Mars

USGS Publications Warehouse

Milazzo, M.P.; Keszthelyi, L.P.; Jaeger, W.L.; Rosiek, M.; Mattson, S.; Verba, C.; Beyer, R.A.; Geissler, P.E.; McEwen, A.S.; ,

2009-01-01

We report on the discovery of columnar jointing in Marte Valles, Mars. These columnar lavas were discovered in the wall of a pristine, 16-km-diameter impact crater and exhibit the features of terrestrial columnar basalts. There are discontinuous outcrops along the entire crater wall, suggesting that the columnar rocks covered a surface area of at least 200 km2, assuming that the rocks obliterated by the impact event were similarly jointed. We also see columns in the walls of other fresh craters in the nearby volcanic plains of Elysium Planitia–Amazonis Planitia, which include Marte Vallis, and in a well-preserved crater in northeast Hellas.

Distribution and evolution of scalloped terrain in the southern hemisphere, Mars

NASA Astrophysics Data System (ADS)

Zanetti, Michael; Hiesinger, Harald; Reiss, Dennis; Hauber, Ernst; Neukum, Gerhard

2010-04-01

Scalloped depressions are a unique martian surface morphology found in the northern and southern hemisphere latitude-dependent dust and ice-rich surface mantles. These features exhibit a distinct asymmetric north-south slope profile, characterized by steep pole-facing scarps, flat floors and gentle equator-facing slopes. We examined High Resolution Stereo Camera (HRSC) images of the southern hemisphere to determine their longitudinal distribution, which revealed that a majority of scalloped terrain is located in the region of the southern wall of the Hellas Basin and northern Malea Planum. A detailed map of this area was produced where scallops were found to contour the southern wall of the basin, and where the ice-rich mantle was seen to be thickest. Scalloped terrain is concentrated along the topographic highs near the Amphitrites and Peneus Paterae and areal extent and depth decreases with increasing depth into the basin. We also examined existing hypothesis for the formation and evolution of scalloped depressions using High Resolution Imaging Science Experiment (HiRISE) images and data from the Thermal Emission Imaging System-Infrared (THEMIS-IR) and the Thermal Emission Spectrometer (TES). Our approach provides regional context for the development of scalloped terrains within the southern hemisphere, and offers detailed evidence of scallop depressions forming around small cracks, presumably caused by thermal contraction. Morphometric measurements show that scalloped depressions can be as much as 40 m deep, with typical depths of between 10 and 20 m. Our observations of scallop formation and development in the southern hemisphere support a solar-insolation model proposed by previous researchers (e.g. [Morgenstern, A., Hauber, E., Reiss, D., van Gasselt, S., Grosse, G., Schirrmeister, L., 2007. J. Geophys. Res. 112, CiteID E06010; Lefort, A., Russell, P.S., Thomas, N., McEwen, A.S., Dundas, C.M., Kirk, R.L., 2009a. J. Geophys. Res. 114, E04005; Lefort, A., Russell, P.S., Thomas, N., 2009b. Icarus, in press]). Observations made using HiRISE images suggest that scalloped depressions most likely form from small cracks in the mantle, which become larger and deeper through sublimation of interstitial ice from within the mantle. Sublimation is likely enhanced on equator-facing slopes because of increased solar insolation, which accounts for the asymmetric slope profile and hemispherical orientation and is demonstrated by THEMIS-IR images. We suggest that sublimation lag deposits can possibly be removed by dust devils or strong slope winds related to the Hellas Basin, offering an explanation as to why scalloped terrain is so abundant only in this area of the southern hemisphere. Daytime maximum summer temperatures suggest that sublimation in the study area of Malea Planum is possible under current conditions if the sublimation lag is removed. While it cannot be ruled out that scalloped terrain in Malea Planum is presently evolving, we attribute the extensive distribution to geologically recent obliquity excursions when conditions were more conducive to mesoscale modification of the ice-rich mantle.

The Specters of Mars

NASA Image and Video Library

2017-07-13

This image from NASA's Mars Reconnaissance Orbiter shows Malea Planum,a polar region in the Southern hemisphere of Mars, directly south of Hellas Basin, which contains the lowest point of elevation on the planet. The region contains ancient volcanoes of a certain type, referred to as "paterae." Patera is the Latin word for a shallow drinking bowl, and was first applied to volcanic-looking features, with scalloped-edged calderas. Malea is also a low-lying plain, known to be covered in dust. These two pieces of information provide regional context that aid our understanding of the scene and features contained in our image. The area rises gradually to a ridge (which can be seen in this Context Camera image) and light-colored dust is blown away by gusts of the Martian wind, which accelerate up the slope to the ridge, leading to more sharp angles of contact between light and dark surface materials. https://photojournal.jpl.nasa.gov/catalog/PIA21784

Physical properties of lava flows on the southwest flank of Tyrrhena Patera, Mars

NASA Technical Reports Server (NTRS)

Crown, David A.; Porter, Tracy K.; Greeley, Ronald

1991-01-01

Tyrrhena Patera (TP) (22 degrees S, 253.5 degrees W), a large, low-relief volcano located in the ancient southern highlands of Mars, is one of four highland paterae thought to be structurally associated with the Hellas basin. The highland paterae are Hesperian in age and among the oldest central vent volcanoes on Mars. The morphology and distribution of units in the eroded shield of TP are consistent with the emplacement of pyroclastic flows. A large flank unit extending from TP to the SW contains well-defined lava flow lobes and leveed channels. This flank unit is the first definitive evidence of effusive volcanic activity associated with the highland paterae and may include the best preserved lava flows observed in the Southern Hemisphere of Mars. Flank flow unit averages, channelized flow, flow thickness, and yield strength estimates are discussed. Analysis suggests the temporal evolution of Martian magmas.

Mars - Hellas Planitia gravity analysis

NASA Technical Reports Server (NTRS)

Sjogren, W. L.; Wimberley, R. N.

1981-01-01

Doppler radio tracking data from Viking Orbiter 1 has provided new detailed observations of gravity variations over Hellas Planitia. Line-of-sight Bouguer gravity definitely indicates that isostatic adjustment has occurred. Two theoretical models were tested to obtain fits to the gravity data. Results for a surface deficit model, and a model with a surface deficit and a mass excess at depth are displayed. The mass-at-depth model produced very marked improvement in the data fit as compared to the surface deficit model. The optimum depth for the mass excess is 130 km.

On the Stability of Liquid Water on Present Day Mars

NASA Technical Reports Server (NTRS)

Haberle, Robert M.; DeVincenzi, Donald L. (Technical Monitor)

2000-01-01

The mean annual surface pressure and temperature on present day Mars do not allow for the long term stability of liquid water on the surface. However, theoretical arguments have been advanced that suggest liquid water could form in transient events even though it would not be in equilibrium with the environment. Using a Mars General Circulation Model, we calculate where and for how long the surface pressure and surface temperature meet the minimum requirements for this metastability of liquid water. These requirements are that the pressure and temperature must be above the triple point of water, but below its boiling point. We find that there are five regions on Mars where these requirements are periodically satisfied: in the near equatorial regions of Amazonis, Arabia, and Elysium, and in the Hellas and Argyre impact basins. Whether liquid water ever forms in these regions depends on the availability of ice and heat, and on the evaporation rate. The latter is poorly understood for low pressure CO2 environments, but is likely to be so high that melting occurs rarely, if at all. However, in the relatively recent past, surface pressures may have been higher than they are today perhaps by as much as a factor of 2 or 3. Under these circumstances melting would have been easier to achieve. We plan to undertake laboratory experiments to better understand the potential for melting in low pressure environments.

Evidence of mud volcanism rooted in gas hydrate-rich cryosphere linking surface and subsurface for the search for life on Mars

NASA Astrophysics Data System (ADS)

De Toffoli, Barbara; Pozzobon, Riccardo; Mazzarini, Francesco; Massironi, Matteo; Cremonese, Gabriele

2017-04-01

We mapped around 6000 mounds in three different portions of the Martian surface on an average area of about 90.000 Km2 for each region. The study areas are located in Hellas basin, Utopia basin and a portion of the Northern Plains lying north of Arabia Terra, between Acidalia and Utopia Planitia. The aim of the study was to understand the nature of the observed features, particularly if they could be interpreted as mud volcanoes or not, and improve our knowledge about the Martian mound fields origin. The analysis of Context Camera (onboard Mars Reconnaissance Orbiter) images showed circular, elliptical and coalescent mounds with central and/or distal pits and flow features such as concentric annular lobes around the source pits and apron-like extensions. We produced DTMs and then high-to-diameter morphometric analysis on two groups of mounds located in Utopia and Hellas basins to enhance the geomorphological observations. We inferred, by means of cluster and fractal analyses, the thickness of the medium cracked by connected fractures and, consequently, the depths of reservoirs that fed the mounds. We found that the fields, which are seated at different latitudes, has been fed, at least partially, by reservoirs located at the base of the gas hydrate stability zone according to Clifford et al., 2010. This evidence produces a meaningful relationship between the clathrates distribution underneath the Martian surface and the occurrence of mound fields on the surface leading to the assumption that the involvement of water, ostensibly as a result of gas hydrate dissociation, plays a key role in the subsurface processes that potentially worked as triggers. These outcomes corroborate the hypothesis that the mapped mounds are actually mud volcanoes and make these structures outstanding targets for astrobiology and habitability studies. In fact, mud volcanoes, extruding material from depths that are still not affordable by our present-day instrumentations, could have sampled and brought to the surface with the sediments a putative extinct or extant deep biosphere. In conclusion, on the base of this study, emerged that: (i) mud volcanoes are the best terrestrial analogs for the considered Martian mounds, (ii) there is a recurrent specific subsurface environment where the phenomenon may be triggered and it is the base of gas hydrate-rich cryosphere for all the study areas and (iii) mud volcanism seems to be, at least partially, a geologically recent event in terms of planet thermal evolution timespan. In light of these results, the CaSSIS camera, onboard the Trace Gas Orbiter ExoMARS mission, will provide new images of these features to improve and widen the understanding of the mechanisms that lie behind this phenomenon.

The Location and most Viable Magnetic Mineral of the Magnetic Layer of Mars Crust

NASA Astrophysics Data System (ADS)

Boutin, D.; Arkani-Hamed, J.

2010-12-01

The discovery of strong magnetic anomalies of remanant origin over the southern hemisphere of Mars [1] has provided the challenge to estimate the thickness of the magnetic crust and identify magnetic minerals capable of producing the anomalies. The power spectral analysis of the magnetic anomalies suggests a magnetic crust of 46 km thickness [2]. Estimates of depth to Curie temperature of viable magnetic mineral at about 4 Ga imply that the potentially magnetic layer must have been in the upper 70 km of the crust [3], and that the lower ~10 km must have been effectively demagnetized since by viscous decay [4]. The rock magnetic measurements show appreciable demagnetization at hydrostatic pressures up to 1.2 GPa [5], consistent with the above estimate of the magnetic layer thickness. The distinct lack of magnetic signature of many giant impact basins indicates that the impacts have demagnetized the crust. Detailed study of the magnetic anomalies surrounding Hellas, Isidis, and Argyre suggests that the area inside ~80% of the basin radius is almost completely demagnetized [6], as is confirmed by recent investigations [7,8]. First we use the evidence from these giant basins and show that Pierazzo et al. [1997] shock pressure distribution model with maximum decay exponent is most viable for Martian crust among the 6 models proposed. Using this model, we then determine the demagnetization of the crust by impacts that can create 10-500 km diameter craters. The surface of Mars is saturated by craters of diameters <100 km, which have completely demagnetized the upper ~10 km of Mars. The impacts that create 200-500 km diameter craters are capable of demagnetizing the entire crust beneath the craters. Second, we model topography, gravity, and magnetic data over all craters of diameters 300-600 km located in the southern hemisphere of Mars. The topography and gravity data suggest that majority of the craters are isostatically compensated and have distinct mantle plugs directly beneath, suggesting that impacts have effectively disturbed the crust. Many of the craters have well-defined magnetic signatures. Modeling a magnetic anomaly under the assumption that a) the mantle plug beneath a crater is non magnetic, b) the anomaly is due to impact demagnetization of the crust, and c) the impact heating has elevated the temperature and further enhanced viscous decay of magnetization in the lower part of the crust, provides a means to identify magnetite as the most viable magnetic carrier in the Martian crust. [1] Acuña, M.H. et al., Science 284, 790-793, 1999. [2] Voorhies, C.V. JGR, 821, 113, E04004, 2008. [3] Arkani-Hamed, J., JGR,110, 585, E08005, 2005. [4] Shahnas, H. and J. Arkani-Hamed, JGR, 112, E02009, 2007. [5] Bezaeva, N.S. et al., PEPI, 197, 7-20, 2010. [6] Mohit, P.S. and J. Arkani-Hamed, Icarus 168, 305-317, 2004. [7] Lillis, R.J.,et al., LPSC, XL, Abs. No. 1444, 2009. [8] Louzada, K.L., et al., EPSL, submitted, 2010. [9] Pierazzo, E. et al., Icarus 127, 408-423, 1997.

Geology of -30247, -35247, and -40247 Quadrangles, Southern Hesperia Planum, Mars

NASA Technical Reports Server (NTRS)

Mest, S. C.; Crown, D. A.

2010-01-01

Geologic mapping of MTM -30247, -35247, and -40247 quadrangles is being used to characterize Reull Vallis (RV) and examine the roles and timing of volatile-driven erosional and depositional processes. This study complements earlier investigations of the eastern Hellas region, including regional analyses [1-6], mapping studies of circum-Hellas canyons [7-10], and volcanic studies of Hadriaca and Tyrrhena Paterae [11-13]. Key scientific objectives include 1) characterizing RV in its "fluvial zone," and evaluating its history of formation, 2) analyzing channels in the surrounding plains and potential connections to RV, and 3) examining young, possibly sedimentary plains along RV.

Why the New Gully Deposits are Not Dry Dust Slope Streaks

NASA Image and Video Library

2006-12-06

The light-toned deposits that formed in two gully sites on Mars during the Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) mission in the 1999 to 2005 period are considered to be the result of sediment transport by a fluid with the physical properties of liquid water. The young, light-toned gully deposits were found in a crater in Terra Sirenum (see PIA09027 or MOC2-1618) and in a crater east of the Hellas basin in the Centauri Montes region (see PIA09028 or MOC2-1619). In their study of how the light-toned gully deposits may have formed, the MOC team considered their resemblance to light- and dark-toned slope streaks found elsewhere on Mars. Slope streaks are most commonly believed to have formed by downslope movement of extremely dry, very fine-grained dust, through processes thought by some to be analogous to terrestrial snow avalanche formation. http://photojournal.jpl.nasa.gov/catalog/PIA09030

Map of Martian Potassium at Mid-Latitudes

NASA Image and Video Library

2003-03-13

This gamma ray spectrometer map of the mid-latitude region of Mars is based on gamma-rays from the element potassium. Potassium, having the chemical symbol K, is a naturally radioactive element and is a minor constituent of rocks on the surface of both Mars and Earth. The region of highest potassium content, shown in red, is concentrated in the northern part of Acidalia Planitia (centered near 55 degrees N, -30 degrees). Several areas of low potassium content, shown in blue, are distributed across the mid-latitudes, with two significant low concentrations, one associated with the Hellas Basin (centered near 35 degrees S, 70 degrees) and the other lying southeast of Elysium Mons (centered near 10 degrees N, 160 degrees). Contours of constant surface elevation are also shown. The long continuous line running from east to west marks the approximate separation of the younger lowlands in the north from the older highlands in the south. http://photojournal.jpl.nasa.gov/catalog/PIA04255

Episodic Endogenetic-driven Atmospheric and Hydrologic Cycles and Their Influence on the Geologic Records of the Northern and Southern Hemispheres, Mars

NASA Technical Reports Server (NTRS)

Dohm, J. M.; Fairen, A. G.; Baker, V. R.; Ferris, J. C.; Anderson, R. C.; Uceda, E. R.

2003-01-01

Diverse evidence shows a direct correlation between episodic endogenetic events of the Tharsis magmatic complex (TMC)/Superplume, flood inundations in the northern plains, and glacial/ lacustrine/ice sheet activity in the south polar region, which includes Hellas and Argyre impact basins, corroborating the MEGAOUTFLO hypothesis. The TMC encompasses a total surface area of approximately 2 x 10(exp 7) sq km, which is slightly larger than the estimated size of the Southern Pacific Superplume. These hydrologic events include: (1) a Noachian to possibly Early Hesperian oceanic epoch and related atmospheric and environmental change (a water body covering about 1/3 of the planet s surface area) related to the incipient development of Tharsis Superplume and the northwestern sloping valleys (NSVs) and possibly early circum-Chryse development, the northwest and northeast watersheds of Tharsis, respectively, (2) a smaller ocean inset within the former larger ocean related to extensive Late Hesperian to Early Amazonian effusive volcanism at Tharsis and Elysium and incisement of the circum-Chryse outflow system. During this time, magmatic/plume-driven tectonic activity transitioned into more centralized volcanism. This Late Hesperian water body may have simply diminished into smaller seas and/or lakes during the Amazonian Period, or renewed activity at Tharsis and Elysium resulted in brief perturbations from the prevailing cold and dry climatic conditions to later form minor seas or lakes. All of the hydrologic phases transitioned into extensive periods of quiescence.

Dynamic Mars

NASA Image and Video Library

2015-09-30

This image from NASA Mars Reconnaissance Orbiter spacecraft shows a channel system flowing to the southwest toward the huge Hellas impact basin. Click on the image for larger version The scarp at the edge of the North Polar layered deposits of Mars is the site of the most frequent frost avalanches seen by HiRISE. At this season, northern spring, frost avalanches are common and HiRISE monitors the scarp to learn more about the timing and frequency of the avalanches, and their relationship to the evolution of frost on the flat ground above and below the scarp. This picture managed to capture a small avalanche in progress, right in the color strip. See if you can spot it in the browse image, and then click on the cutout to see it at full resolution. The small white cloud in front of the brick red cliff is likely carbon dioxide frost dislodged from the layers above, caught in the act of cascading down the cliff. It is larger than it looks, more than 20 meters across, and (based on previous examples) it will likely kick up clouds of dust when it hits the ground. The avalanches tend to take place at a season when the North Polar region is warming, suggesting that the avalanches may be triggered by thermal expansion. The avalanches remind us, along with active sand dunes, dust devils, slope streaks and recurring slope lineae, that Mars is an active and dynamic planet. http://photojournal.jpl.nasa.gov/catalog/PIA19961

Subsurface Structure and the Stress State of the Utopia Basin, Mars

NASA Astrophysics Data System (ADS)

Searls, M. L.; Phillips, R. J.

2005-12-01

A great deal of work has been done in determining the resurfacing history of the northern lowlands; however, most of the previous research has focused on the depth and characteristics of the Hesperian and Amazonian plains units that cover an older, heavily cratered Noachian surface (e.g. Tanaka et. al. 2003). An analysis of the amount and density of fill within the Utopia Basin could provide valuable insight to the depositional environment of the northern lowlands during the earliest epoch of martian history. In the present study we use the topography and gravity data from recent Mars' missions to analyze the subsurface structure of the Utopia basin, focusing on the volume and density of fill that causes the shallowness of the basin. Using the assumption that the initial isostatic state of Utopia was similar to that of the Hellas basin allows us to construct a model for Utopia that facilitates investigation of its interior configuration. Based on the spherical harmonic, thin-shell elastic model of Banerdt (1986), we developed a system of equations that allows us to solve for the original basin shape, the amount of fill within Utopia basin, the amount of flexure due to the fill material, the total vertical load and the horizontal load potential. The presence of quasi-circular depressions within the Utopia basin (Frey 2004) indicates that the majority of the material within Utopia was deposited early in the Noachian when the elastic lithosphere of Mars was (presumably) relatively thin (<50 km). Given this constraint along with constraints placed on the system due to the pre-fill isostatic assumption, we can place a lower bound on the density of the fill within Utopia basin of 2800 kg/m3. This indicates that the amount of fill within the Utopia basin is >15 km, with a corresponding lithospheric flexure/membrane deformation of >14 km. The high density obtained for the fill requires that it contain a large igneous component, the source of which is problematic. Relaxing the isostatic assumption to a reasonable degree perturbs the density bound only slightly. This thin-shell model also allows us to calculate the stress field due to the flexure/membrane strains. The stress results show that the circumferential and radial tectonic features seen in the Utopia region (Thomson and Head 2001) are not due solely to deformation of the elastic lithosphere, so the tectonic features observed are the result, at least in part, of processes that occur within the load itself.

Ripples and Dunes

NASA Technical Reports Server (NTRS)

2006-01-01

27 May 2006 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows dark sand dunes on the floor of an impact crater west of Hellas Planitia. Portions of the crater floor are exposed near the center and lower right corner of the image but, in general, the floor is covered by large, windblown ripples. The dark dune sand typically covers ripples, indicating that the dunes are younger and made of a more mobile material.

Location near: 43.7oS, 320.4oW Image width: 3 km (1.9 mi) Illumination from: upper left Season: Southern Summer

Abstracts of the Annual Meeting of Planetary Geologic Mappers, Flagstaff, AZ, 2010

NASA Technical Reports Server (NTRS)

Bleamaster, Leslie F., III (Editor); Tanaka, Kenneth L. (Editor); Kelley, Michael S. (Editor)

2010-01-01

Topics covered include: Detailed Analysis of the Intra-Ejecta Dark Plains of Caloris Basin, Mercury; The Formation and Evolution of Tessera and Insights into the Beginning of Recorded History on Venus: Geology of the Fortuna Tessera Quadrangle (V-2); Geologic Map of the Snegurochka Planitia Quadrangle (V-1): Implications for the Volcanic History of the North Polar Region of Venus; Geological Map of the Fredegonade (V-57) Quadrangle, Venus: Status Report; Geologic Mapping of V-19; Geology of the Lachesis Tessera Quadrangle (V-18), Venus; Comparison of Mapping Tessera Terrain in the Phoebe Regio (V-41) and Tellus Tessera (V-10) Quadrangles; Geologic Mapping of the Devana Chasma (V-29) Quadrangle, Venus; Geologic Mapping of the Aristarchus Plateau Region on the Moon; Geologic Mapping of the Lunar South Pole Quadrangle (LQ-30); The Pilot Lunar Geologic Mapping Project: Summary Results and Recommendations from the Copernicus Quadrangle; Geologic Mapping of the Nili Fossae Region of Mars: MTM Quadrangles 20287, 20282, 25287, 25282, 30287, and 30282; Geologic Mapping of the Mawrth Vallis Region, Mars: MTM Quadrangles 25022, 25017, 25012, 20022, 20017, and 20012; Evidence for an Ancient Buried Landscape on the NW Rim of Hellas Basin, Mars; New Geologic Map of the Argyre Region of Mars: Deciphering the Geologic History Through Mars Global Surveyor, Mars Odyssey, and Mars Express Data; Geologic Mapping in the Hesperia Planum Region of Mars; Geologic Mapping of the Meridiani Region of Mars; Geologic Mapping in Southern Margaritifer Terra; Geology of -30247, -35247, and -40247 Quadrangles, Southern Hesperia Planum, Mars; The Interaction of Impact Melt, Impact-Derived Sediment, and Volatiles at Crater Tooting, Mars; Geologic Map of the Olympia Cavi Region of Mars (MTM 85200): A Summary of Tactical Approaches; Geology of the Terra Cimmeria-Utopia Planitia Highland Lowland Transitional Zone: Final Technical Approach and Scientific Results; Geology of Libya Montes and the Interbasin Plains of Northern Tyrrhena Terra, Mars: First Year Results and Second Year Work Plan; Mars Global Geologic Mapping Progress and Suggested Geographic-Based Hierarchal Systems for Unit Grouping and Naming; Progress in the Scandia Region Geologic Map of Mars; Geomorphic Mapping of MTMS -20022 and -20017; Geologic Mapping of the Medusae Fossae Formation, Mars, and the Northern Lowland Plains, Venus; Volcanism on Io: Results from Global Geologic Mapping; Employing Geodatabases for Planetary Mapping Conduct - Requirements, Concepts and Solutions; and Planetary Geologic Mapping Handbook - 2010.

Niger Vallis

NASA Technical Reports Server (NTRS)

2003-01-01

[figure removed for brevity, see original site]

Released 24 September 2003

Named for a great river in Africa, the martian version is a system of eroding channels that empties into the Hellas impact basin. One style of erosion is evident in this image, where the upper branches of the Niger are merging. Some process weakens the crust until it founders, producing large slump blocks that continue to erode. This process enlarges the channels and ultimately may lead to a single upper channel.

Image information: VIS instrument. Latitude -34.7, Longitude 92.6 East (267.4 West). 19 meter/pixel resolution.

Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time.

NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is led by Dr. Philip Christensen at Arizona State University. Lockheed Martin Astronautics, Denver, is the prime contractor for the Odyssey project, and developed and built the orbiter. Mission operations are conducted jointly from Lockheed Martin and from JPL, a division of the California Institute of Technology in Pasadena.

Pandora Fretum Crater

NASA Technical Reports Server (NTRS)

2002-01-01

[figure removed for brevity, see original site] (Released 26 July 2002) Another in a series of craters with unusual interior deposits, this THEMIS image shows an unnamed crater in the southern hemisphere Pandora Fretum region near the Hellas Basin. Craters with eroded layered deposits are quite common on Mars but the crusty textured domes in the center of the image make this crater more unusual. Looking vaguely like granitic intrusions, there erosional style is distinct from the rest of the interior deposit which shows a very obvious layered morphology. While it is unlikely that the domes are granite plutons, it is possible that they do represent some other shallowly emplaced magmatic intrusion. More likely still is that variations in induration of the layered deposit allow for variations in the erosional morphology. Note how the surface of the crater floor in the northernmost portion of the image has a texture similar to that of the domes. This may represent an incipient form of the erosion that has produced the domes but has not progressed as far. An analysis of other craters in the area may shed light on the origin of the domes.

The Tyrrhena-Malea Volcanic Province, Mars: Overview

NASA Astrophysics Data System (ADS)

Williams, D.; Greeley, R.; Ferguson, R.; Kuzmin, R.; McCord, T.; Combe, J.-P.; Head, J.; Xiao, L.; Manfredi, L.; Poulet, F.; Pinet, P.; Baratoux, D.; Plaut, J. J.; Raitala, J.; Neukum, G.

2008-09-01

Building on previous studies of volcanoes around the Hellas basin with new studies of imaging (HRSC, THEMIS, MOC, HiRISE, CTX), multispectral (HRSC, OMEGA), topographic (MOLA) and gravity data, we define a new Martian volcanic province as the Tyrrhena-Malea Volcanic Province (T-MVP). With an area of >2.1 million sq. km, it contains the six oldest central vent volcanoes on Mars, which formed after the Hellas impact basin, between 4.0 to 3.6 Ga. These volcanoes mark a transition from the flood volcanism that formed Malea Planum ~3.8 Ga, to localized point source eruptions. The T-MVP volcanoes have two general morphologies: 1) shieldlike edifices (Tyrrhena, Hadriaca, and Amphitrites Paterae), and 2) caldera-like depressions surrounded by ridged plains (Peneus, Malea, and Pityusa Paterae). Positive gravity anomalies are found at Tyrrhena, Hadriaca, and Amphitrites, perhaps indicative of dense magma bodies below the surface. The lack of shield-like edifices and weak gravity anomalies at Peneus, Malea, and Pityusa suggest a fundamental difference in their formation, styles of eruption, and/or compositions. The northernmost volcanoes, the ~3.7- 3.9 Ga Tyrrhena and Hadriaca Paterae, have low slopes, well-channeled flanks, and smooth caldera floors (at tens of meters/pixel scale), indicative of ash shields formed from poorly-consolidated pyroclastic deposits that have been modified by fluvial and aeolian erosion and deposition. The ~3.6 Ga Amphitrites Patera also has a well-channeled flank, but it and the ~3.8 Ga Peneus Patera are dominated by scalloped and pitted terrain, pedestal and ejecta flow craters, and a general `softened' appearance. This morphology is indicative not only of surface materials subjected to periglacial processes involving water ice, but also of a surface composed of easily eroded materials such as ash and dust. The southernmost volcanoes, the ~3.8 Ga Malea and Pityusa Paterae, have no channeled flanks, no scalloped and pitted terrain, and lack the `softened' appearance of their surfaces, but they do contain pedestal and ejecta flow craters and large, smooth, bright plateaus in their central depressions. This morphology is indicative of a surface with not only a high water ice content, but also a more consolidated material that is less susceptible to degradation (relative to the other four volcanoes). We suggest that Malea and Pityusa (and possibly Peneus) Paterae are Martian equivalents to Earth's giant calderas (e.g., Yellowstone, Long Valley) that erupted large volumes of volcanic materials, and that Malea and Pityusa are probably composed of either lava flows or ignimbrites. HRSC and OMEGA spectral data indicate that dark gray to slightly red materials (often represented as blue or black pixels in HRSC color images), found in the patera floors and topographic lows throughout the T-MVP, have a basaltic composition. A key issue is whether this dark material represents concentrations of underlying basaltic material exposed by aeolian winnowing, or if the material was transported from elsewhere on Mars by regional winds. Understanding the provenance of these dark materials may be the key to understanding the volcanic diversity of the Tyrrhena-Malea Volcanic Province. References [1] Crown, D. and Greeley, R. (2007) U.S. Geol. Surv. Sci. Inves. Ser. Map 2936. [2] Gregg, T., et al. (1998) U.S. Geol. Surv. Map I- 2556. [3] Leonard, G. and Tanaka, K. (2001) U. S. Geol. Survey Misc. Invest. Series Map I-2694. [4] Kolb, E. and Tanaka, K. (2008) Geologic Map of the Planum Australe Region of Mars. U. S. Geol. Survey. Misc. Investigation Series, in review. [5] Peterson, J. (1978) Proc. 9th LPSC, 3411-3432.

77 FR 75189 - Certain Light-Emitting Diodes and Products Containing Same; Commission Determination Not To...

Federal Register 2010, 2011, 2012, 2013, 2014

2012-12-19

... Corporate Center USA, Hella, Inc., Automotive Lighting Reutlingen GmbH, Automotive Lighting LLC, Tecnologia..., Inc., Automotive Lighting Reutlingen GmbH, Automotive Lighting, LLC, and [[Page 75190

The Origin of the Terra Meridiani Sediments: Volatile Transport and the Formation of Sulfate Bearing Layered Deposits on Mars

NASA Technical Reports Server (NTRS)

Niles, P.B.

2008-01-01

The chemistry, sedimentology, and geology of the Meridiani sedimentary deposits are best explained by eolian reworking of the sublimation residue of a large scale ice/dust deposit. This large ice deposit was located in close proximity to Terra Meridiani and incorporated large amounts of dust, sand, and SO2 aerosols generated by impacts and volcanism during early martian history. Sulfate formation and chemical weathering of the initial igneous material is hypothesized to have occurred inside of the ice when the darker mineral grains were heated by solar radiant energy. This created conditions in which small films of liquid water were created in and around the mineral grains. This water dissolved the SO2 and reacted with the mineral grains forming an acidic environment under low water/rock conditions. Subsequent sublimation of this ice deposit left behind large amounts of weathered sublimation residue which became the source material for the eolian process that deposited the Terra Meridiani deposit. The following features of the Meridiani sediments are best explained by this model: The large scale of the deposit, its mineralogic similarity across large distances, the cation-conservative nature of the weathering processes, the presence of acidic groundwaters on a basaltic planet, the accumulation of a thick sedimentary sequence outside of a topographic basin, and the low water/rock ratio needed to explain the presence of very soluble minerals and elements in the deposit. Remote sensing studies have linked the Meridiani deposits to a number of other martian surface features through mineralogic similarities, geomorphic similarities, and regional associations. These include layered deposits in Arabia Terra, interior layered deposits in the Valles Marineris system, southern Elysium/Aeolis, Amazonis Planitia, and the Hellas basin, Aram Chaos, Aureum Chaos, and Ioni Chaos. The common properties shared by these deposits suggest that all of these deposits share a common formation process which must have acted over a large area of Mars. The results of this study suggest a mechanism for volatile transport on Mars without invoking an early greenhouse. They also imply a common formation mechanism for most of the sulfate minerals and layered deposits on Mars, which explains their common occurrence.

Polygonal Ridge Networks on Mars

NASA Astrophysics Data System (ADS)

Kerber, Laura; Dickson, James; Grosfils, Eric; Head, James W.

2016-10-01

Polygonal ridge networks, also known as boxwork or reticulate ridges, are found in numerous locations and geological contexts across Mars. While networks formed from mineralized fractures hint at hot, possibly life-sustaining circulating ground waters, networks formed by impact-driven clasting diking, magmatic dikes, gas escape, or lava flows do not have the same astrobiological implications. Distinguishing the morphologies and geological context of the ridge networks sheds light on their potential as astrobiological and mineral resource sites of interest. The most widespread type of ridge morphology is characteristic of the Nili Fossae and Nilosyrtis region and consists of thin, criss-crossing ridges with a variety of heights, widths, and intersection angles. They are found in ancient Noachian terrains at a variety of altitudes and geographic locations and may be a mixture of clastic dikes, brecciated dikes, and mineral veins. They occur in the same general areas as valley networks and ancient lake basins, but they are not more numerous where these features are concentrated, and can appear in places where they morphologies are absent. Similarly, some of the ridge networks are associated with hydrated mineral detections, but some occur in locations without detections. Smaller, light-toned ridges of variable widths have been found in Gale Crater and other rover sites and are interpreted to be smaller version of the Nili-like ridges, in this case formed by the mineralization of fractures. This type of ridge is likely to be found in many other places on Mars as more high-resolution data becomes available. Hellas Basin is host to a third type of ridge morphology consisting of large, thick, light-toned ridges forming regular polygons at several superimposed scales. While still enigmatic, these are most likely to be the result of sediment-filled fractures. The Eastern Medusae Fossae Formation contains large swaths of a fourth, previously undocumented, ridge network type. The dark ridges, reaching up to 50 m in height, enclose regular polygons and erode into dark boulders. These ridge networks are interpreted to form as a result of lava flow embayment of deeply fractured Medusae Fossae Formation outcrops.

Which processes form the volcanic sands on Mars?

NASA Astrophysics Data System (ADS)

Grégoire, M.; Baratoux, D.; Mangold, N.; Arnalds, O.; Platvoet, B.; Bardinzeff, J.; Pinet, P.

2007-12-01

Volcanic sands are common at the surface of Mars. They are usually of basaltic composition. Occurrence of sands, mostly recognized as dark dune fields include numerous impact craters in the southern hemisphere [1], several volcanic provinces such as Cerberus and Syrtis Major[2], several impact craters in the northern hemisphere, the large basins (Hellas and Argyre), Valles Marineris, and the poles [3]. In most cases, the sands are of basaltic composition [2,4], at the exception of the polar dunes which are made of sulfates [3]. It is interesting to note that dunes have been found on the Hesperian volcanic plateau of Systis Major, while they are not reported on Tyrrhena Terra, a volcanic province similar in age and morphology to Syrtis. It seems thus that the formation of sand from volcanic material is not systematic and thus requires particular conditions. These different situations which will be presented raise the following questions. When did these volcanic sands form in the Martian history? Did they result from a long-standing and slow process operating in the present cold conditions or did they result from several episodes associated for instant to climate changes? We review several mechanisms which could account for the formation of volcanic sand on Mars from the volcanic material. In particular, we focus on the role of cold-climate processes from an analysis of terrestrial analogs in Iceland. In this case, the advance and retreat of glaciers over a recent erupted shield volcano associated with the strong catabatic winds have resulted in the rapid formation (less than few thousands years) of large volumes of sands. [1] Fenton, L. K. (2005), Potential sand sources for the dune fields in Noachis Terra, Mars, J. Geophys. Res. 110, E11004, doi :10.1029/2005JE002436. [2] Vaucher et. al, in revision for Icarus [3] Langevin et. al, (2005), Science, 307, 1584-1586 [4] Poulet F., Mangold N. and Erard S. (2003), Astron. & Astrophys. 412, L19-L23.

Peneus Patera

NASA Image and Video Library

2011-07-08

The unusual shallow, scalloped depressions in this image from NASA 2001 Mars Odyssey spacecraft are located on the margin Peneus Patera, south of Hellas Planitia. It may be that volatiles, such as ice, are involved in the formation of these depressions.

The Distribution of Subsurface Water at Hadriaca and Tyrrhena Paterae and Surrounding Areas on Mars from Impact Crater Morphology

NASA Astrophysics Data System (ADS)

Lancaster, M. G.; Guest, J. E.

1996-03-01

It is well established that the surface of Mars exhibits abundant evidence for the presence of either liquid or frozen water during the course of Martian history. The origin, location, extent and transport of this water is of critical importance in the understanding of Martian geology and climate. In particular, the fluid appearance of rampart crater ejecta has been cited as evidence for subsurface ice at the time of impact. Ejecta morphology has proven to be a useful tool for studying the distribution of subsurface ice on Mars. It is possible that in some regions the concentration and distribution of subsurface ice has been affected by volcanic processes, either in the melting and/or mobilisation of existing subsurface water, and/or in the injection of juvenile water into the martian crust. The presence of water may also have affected the style of volcanic eruptions on Mars, increasing the volatile content of rising magmas and generating explosive activity. We are currently investigating the abundance and role of water in the evolution of the volcanoes Hadriaca and Tyrrhena Patera and surrounding highlands northeast of the Hellas Basin. The morphology of these volcanoes has been attributed to explosive volcanism, and to the presence of substantial amounts of water in the regolith at the time of their eruption. The location of Hadriaca Patera in a region containing channelled plains, debris flows, and pitted plains, together with the style of erosion of the volcano flanks suggests presence of volatile-rich surface materials or fluvial or periglacial activity. This work is a continuation of research undertaken by Cave in the Elysium Mons Region, where ice was found to be enriched at depth in the Elysium Lavas. We are performing a similar analysis for the volcanics of Hadriaca and Tyrrhena Paterae. A database containing information on the location, size, morphology, ejecta characteristics and degradation state of several hundred impact craters displaying ejecta in the region of Mars between the equator and 40 degrees S, and from 225 degrees to 275 degrees W is therefore being compiled.

Cancer Risk Map for the Surface of Mars

NASA Technical Reports Server (NTRS)

Kim, Myung-Hee Y.; Cucinotta, Francis A.

2011-01-01

We discuss calculations of the median and 95th percentile cancer risks on the surface of Mars for different solar conditions. The NASA Space Radiation Cancer Risk 2010 model is used to estimate gender and age specific cancer incidence and mortality risks for astronauts exploring Mars. Organ specific fluence spectra and doses for large solar particle events (SPE) and galactic cosmic rays (GCR) at various levels of solar activity are simulated using the HZETRN/QMSFRG computer code, and the 2010 version of the Badhwar and O Neill GCR model. The NASA JSC propensity model of SPE fluence and occurrence is used to consider upper bounds on SPE fluence for increasing mission lengths. In the transport of particles through the Mars atmosphere, a vertical distribution of Mars atmospheric thickness is calculated from the temperature and pressure data of Mars Global Surveyor, and the directional cosine distribution is implemented to describe the spherically distributed atmospheric distance along the slant path at each elevation on Mars. The resultant directional shielding by Mars atmosphere at each elevation is coupled with vehicle and body shielding for organ dose estimates. Astronaut cancer risks are mapped on the global topography of Mars, which was measured by the Mars Orbiter Laser Altimeter. Variation of cancer risk on the surface of Mars is due to a 16-km elevation range, and the large difference is obtained between the Tharsis Montes (Ascraeus, Pavonis, and Arsia) and the Hellas impact basin. Cancer incidence risks are found to be about 2-fold higher than mortality risks with a disproportionate increase in skin and thyroid cancers for all astronauts and breast cancer risk for female astronauts. The number of safe days on Mars to be below radiation limits at the 95th percent confidence level is reported for several Mission design scenarios.

Organ Dose Assessment and Evaluation of Cancer Risk on Mars Surface

NASA Technical Reports Server (NTRS)

Kim, Myung-Hee; Cucinotta, Francis A.

2011-01-01

Organ specific fluence spectra and doses for large solar particle events (SPE) and galactic cosmic rays (GCR) at various levels of solar activity are simulated on the surface of Mars using the HZETRN/QMSFRG computer code and the 2010 version of the Badhwar and O Neill GCR model. The NASA JSC propensity model of SPE fluence and occurrence is used to consider upper bounds on SPE fluence for increasing mission lengths. To account for the radiation transmission through the Mars atmosphere, a vertical distribution of Mars atmospheric thickness is calculated from the temperature and pressure data of Mars Global Surveyor. To describe the spherically distributed atmospheric distance on the Mars surface at each elevation, the directional cosine distribution is implemented. The resultant directional shielding by Mars atmosphere at each elevation is then coupled with vehicle and body shielding for organ dose estimates. Finally, cancer risks for astronauts exploring Mars can be assessed by applying the NASA Space Radiation Cancer Risk 2010 model with the resultant organ dose estimates. Variations of organ doses and cancer risk quantities on the surface of Mars, which are due to a 16-km elevation range between the Tharsis Montes and the Hellas impact basin, are visualized on the global topography of Mars measured by the Mars Orbiter Laser Altimeter. It is found that cancer incidence risks are about 2-fold higher than mortality risks with a disproportionate increase in skin and thyroid cancers for male and female astronauts and in breast cancer for female astronauts. The number of safe days, defined by the upper 95% percent confidence level to be below cancer limits, on Mars is analyzed for several Mars mission design scenarios.

Changing Styles of Erosion During the Noachian-Hesperian Transition: Evidence for a Possible Climatic Optimum?

NASA Astrophysics Data System (ADS)

Moore, J. M.; Howard, A. D.

2004-11-01

We discuss the changing styles of erosion in the highlands during the Noachian and early Hesperian. Taken together the features we report in this study fit into a hypothesis in which a climate optimum occurred around the Noachian-Hesperian (N-H) boundary imposing the last great act of large-scale Martian fluvial activity. We review the some of the morphologic evidence for a possible N-H climate optimum. The contrast in erosional style between the widespread Noachian erosion and more limited 'pristine' channels (and other features) indicates different climatic regimes. Several scenarios for this change of erosional style, including headward migration of channel knickpoints by sapping, low intensity but continuous precipitation, and basal melting beneath a thick ice cover have been proposed. One possibility is that the limited headward extent of channel incision is best explained by runoff from snowmelt, with development of duricrusts as a contributing factor. Alluvial fans formed during this time period but appear to lack the secondary drainage that occurs on most terrestrial alluvial fans that results from post-depositional runoff erosion. This suggests that the source of water for these fans was restricted to the contributing basins on the crater headwalls. Such headwall alcoves might be natural traps for snowfall. A cold climate with relatively abundant snowfall is also consistent with the possible occurrence of large, possibly ice-covered lakes on the highlands and in Hellas at this time. Runoff might have occurred during favorable obliquity conditions. In addition, the early Hesperian was noted for widespread large-scale volcanic activity, possibly contributing to greenhouse warming and water inventories. Although impact-induced climate optima might aid either enhanced precipitation or snowmelt, the presence of long-lived deltas suggests volcanism or orbital mechanics controlling the N-H climate.

Large-Scale Traveling Weather Systems in Mars’ Southern Extratropics

NASA Astrophysics Data System (ADS)

Hollingsworth, Jeffery L.; Kahre, Melinda A.

2017-10-01

Between late fall and early spring, Mars’ middle- and high-latitude atmosphere supports strong mean equator-to-pole temperature contrasts and an accompanying mean westerly polar vortex. Observations from both the MGS Thermal Emission Spectrometer (TES) and the MRO Mars Climate Sounder (MCS) indicate that a mean baroclinicity-barotropicity supports intense, large-scale eastward traveling weather systems (i.e., transient synoptic-period waves). Such extratropical weather disturbances are critical components of the global circulation as they serve as agents in the transport of heat and momentum, and generalized scalar/tracer quantities (e.g., atmospheric dust, water-vapor and ice clouds). The character of such traveling extratropical synoptic disturbances in Mars' southern hemisphere during late winter through early spring is investigated using a moderately high-resolution Mars global climate model (Mars GCM). This Mars GCM imposes interactively-lifted and radiatively-active dust based on a threshold value of the surface stress. The model exhibits a reasonable "dust cycle" (i.e., globally averaged, a dustier atmosphere during southern spring and summer occurs). Compared to the northern-hemisphere counterparts, the southern synoptic-period weather disturbances and accompanying frontal waves have smaller meridional and zonal scales, and are far less intense. Influences of the zonally asymmetric (i.e., east-west varying) topography on southern large-scale weather are investigated, in addition to large-scale up-slope/down-slope flows and the diurnal cycle. A southern storm zone in late winter and early spring presents in the western hemisphere via orographic influences from the Tharsis highlands, and the Argyre and Hellas impact basins. Geographically localized transient-wave activity diagnostics are constructed that illuminate dynamical differences amongst the simulations and these are presented.

An Expanded Analysis of Nitrogen Ice Convection in Sputnik Planum

NASA Astrophysics Data System (ADS)

Umurhan, Orkan M.; Lyra, Wladimir; Wong, Teresa; McKinnon, William B.; Nimmo, Francis; Howard, Alan D.; Moore, Jeffrey M.; Binzel, Richard; White, Oliver; Stern, S. Alan; Ennico, Kimberly; Olkin, Catherine B.; Weaver, Harold A.; Young, Leslie; New Horizons Geology and Geophysics Science Team

2016-10-01

The New Horizons close-encounter flyby of Pluto revealed 20-35 km scale ovoid patterns on the informally named Sputnik Planum. These features have been recently interpreted and shown to arise from the action of solid-state convection of (predominantly) nitrogen ice driven by Pluto's geothermal gradient. One of the major uncertainties in the convection physics centers on the temperature and grain-size dependency of nitrogen ice rheology, which has strong implications for the overturn times of the convecting ice. Assuming nitrogen ice in Sputnik Planum rests on a passive water ice bedrock that conducts Pluto's interior heat flux, and, given the uncertainty of the grain-size distribution of the nitrogen ice in Sputnik Planum, we examine a suite of two-dimensional convection models that take into account the thermal contact between the nitrogen ice layer and the conducting water-ice bedrock for a given emergent geothermal flux. We find for nitrogen ice layers several km deep, the emerging convection efficiently cools the nitrogen-ice water-ice bedrock interface resulting in temperature differences across the convecting layer of 10-20 K (at most) regardless of layer depth. For grain sizes ranging from 0.01 mm to 5 mm the resulting horizontal size to depth ratios of the emerging convection patterns go from 4:1 up to 6:1, suggesting that the nitrogen ice layer in Sputnik Planum may be anywhere between 3.5 and 8 km deep. Such depths are consistent with Sputnik Planum being a large impact basin (in a relative sense) analogous to Hellas on Mars. In this grain-size range we also find, (i) the calculated cell overturn times are anywhere from 1e4 to 5e5 yrs and, (ii) there is a distinct transition from steady state to time dependent convection.

Large-Scale Traveling Weather Systems in Mars Southern Extratropics

NASA Technical Reports Server (NTRS)

Hollingsworth, Jeffery L.; Kahre, Melinda A.

2017-01-01

Between late fall and early spring, Mars' middle- and high-latitude atmosphere supports strong mean equator-to-pole temperature contrasts and an accompanying mean westerly polar vortex. Observations from both the MGS Thermal Emission Spectrometer (TES) and the MRO Mars Climate Sounder (MCS) indicate that a mean baroclinicity-barotropicity supports intense, large-scale eastward traveling weather systems (i.e., transient synoptic-period waves). Such extratropical weather disturbances are critical components of the global circulation as they serve as agents in the transport of heat and momentum, and generalized scalar/tracer quantities (e.g., atmospheric dust, water-vapor and ice clouds). The character of such traveling extratropical synoptic disturbances in Mars' southern hemisphere during late winter through early spring is investigated using a moderately high-resolution Mars global climate model (Mars GCM). This Mars GCM imposes interactively-lifted and radiatively-active dust based on a threshold value of the surface stress. The model exhibits a reasonable "dust cycle" (i.e., globally averaged, a dustier atmosphere during southern spring and summer occurs). Compared to the northern-hemisphere counterparts, the southern synoptic-period weather disturbances and accompanying frontal waves have smaller meridional and zonal scales, and are far less intense. Influences of the zonally asymmetric (i.e., east-west varying) topography on southern large-scale weather are investigated, in addition to large-scale up-slope/down-slope flows and the diurnal cycle. A southern storm zone in late winter and early spring presents in the western hemisphere via orographic influences from the Tharsis highlands, and the Argyre and Hellas impact basins. Geographically localized transient-wave activity diagnostics are constructed that illuminate dynamical differences amongst the simulations and these are presented.

Simulating Mars' Dust Cycle with a Mars General Circulation Model: Effects of Water Ice Cloud Formation on Dust Lifting Strength and Seasonality

NASA Technical Reports Server (NTRS)

Kahre, Melinda A.; Haberle, Robert; Hollingsworth, Jeffery L.

2012-01-01

The dust cycle is critically important for the current climate of Mars. The radiative effects of dust impact the thermal and dynamical state of the atmosphere [1,2,3]. Although dust is present in the Martian atmosphere throughout the year, the level of dustiness varies with season. The atmosphere is generally the dustiest during northern fall and winter and the least dusty during northern spring and summer [4]. Dust particles are lifted into the atmosphere by dust storms that range in size from meters to thousands of kilometers across [5]. Regional storm activity is enhanced before northern winter solstice (Ls200 degrees - 240 degrees), and after northern solstice (Ls305 degrees - 340 degrees ), which produces elevated atmospheric dust loadings during these periods [5,6,7]. These pre- and post- solstice increases in dust loading are thought to be associated with transient eddy activity in the northern hemisphere with cross-equatorial transport of dust leading to enhanced dust lifting in the southern hemisphere [6]. Interactive dust cycle studies with Mars General Circulation Models (MGCMs) have included the lifting, transport, and sedimentation of radiatively active dust. Although the predicted global dust loadings from these simulations capture some aspects of the observed dust cycle, there are marked differences between the simulated and observed dust cycles [8,9,10]. Most notably, the maximum dust loading is robustly predicted by models to occur near northern winter solstice and is due to dust lifting associated with down slope flows on the flanks of the Hellas basin. Thus far, models have had difficulty simulating the observed pre- and post- solstice peaks in dust loading.

Novel approaches to helicopter obstacle warning

NASA Astrophysics Data System (ADS)

Seidel, Christian; Samuelis, Christian; Wegner, Matthias; Münsterer, Thomas; Rumpf, Thomas; Schwartz, Ingo

2006-05-01

EADS Germany is the world market leader in commercial Helicopter Laser Radar (HELLAS) Obstacle Warning Systems. The HELLAS-Warning System has been introduced into the market in 2000, is in service at German Border Control (Bundespolizei) and Royal Thai Airforce and is successfully evaluated by the Foreign Comparative Test Program (FCT) of the USSOCOM. Currently the successor system HELLAS-Awareness is in development. It will have extended sensor performance, enhanced realtime data processing capabilities and advanced HMI features. We will give an outline of the new sensor unit concerning detection technology and helicopter integration aspects. The system provides a widespread field of view with additional dynamic line of sight steering and a large detection range in combination with a high frame rate of 3Hz. The workflow of the data processing will be presented with focus on novel filter techniques and obstacle classification methods. As commonly known the former are indispensable due to unavoidable statistical measuring errors and solarisation. The amount of information in the filtered raw data is further reduced by ground segmentation. The remaining raised objects are extracted and classified in several stages into different obstacle classes. We will show the prioritization function which orders the obstacles concerning to their threat potential to the helicopter taking into account the actual flight dynamics. The priority of an object determines the display and provision of warnings to the pilot. Possible HMI representation includes video or FLIR overlay on multifunction displays, audio warnings and visualization of information on helmet mounted displays and digital maps. Different concepts will be presented.

New dust opacity mapping from Viking Infrared Thermal Mapper data

NASA Technical Reports Server (NTRS)

Martin, Terry Z.; Richardson, Mark I.

1993-01-01

Global dust opacity mapping for Mars has been carried forward using the approach described by Martin (1986) for Viking IR Thermal Mapper data. New maps are presented for the period from the beginning of Viking observations, until Ls 210 deg in 1979 (1.36 Mars years). This range includes the second and more extensive planet-encircling dust storm observed by Viking, known as storm 1977b. Improvements in approach result in greater time resolution and smaller noise than in the earlier work. A strong local storm event filled the Hellas basin at Ls 170 deg, prior to the 1977a storm. Dust is retained in equatorial regions following the 1977b storm far longer than in mid-latitudes. Minor dust events appear to raise the opacity in northern high latitudes during northern spring. Additional mapping with high time resolution has been done for the periods of time near the major storm origins in order to search for clues to the mechanism of storm initiation. The first evidence of the start of the 1977b storm is pushed back to Ls 274.2 deg, preceding signs of the storm in images by about 15 hours.

Tough times for Greek science

NASA Astrophysics Data System (ADS)

2013-08-01

The recent economic crisis has drastically affected research and development in Greece, but competitive research goes on, says Eleftherios Economou, a founder of the Foundation of Research and Technology Hellas (FORTH) research centre in Greece, and former General Secretary for research and technology.

Martian Dust Cycle

NASA Astrophysics Data System (ADS)

Cantor, B. A.; James, P. B.

The Mars Observer Camera (MOC), aboard Mars Global Surveyor (MGS), has completed approximately 3 consecutive Martian years of global monitoring, since entering its mapping orbit on March 9, 1999. MOC observations have shown the important role that dust devils and dust storms play in the Martian dust cycle on time scales ranging from semi-diurnally to interannually. These dust events have been observed across much of the planet from the depths of Hellas basin to the summit of Arsia Mons and range in size from10s of meters across (dust devils) to planet encircling (global dust veils). Though dust devils occur throughout most of the Martian year, each hemisphere has a "dust devil season" that generally follows the subsolar latitude and appears to be repeatable from year-to-year. An exception is NW Amazonis, which has frequent, large dust devils throughout northern spring and summer. MOC observations show no evidence that dust devils cause or lead to dust storms, however, observations do suggest that dust storms can initiate dust devil activity. Dust devils also might play a role in maintaining the low background dust opacity of the Martian atmosphere. Dust storms occur almost daily with few exceptions, with 1000s occurring each year in the present Martian environment, dispelling the notion of a "Classical Dust Storm Season". However, there does appear to be an annual dust storm cycle, with storms developing in specific locations during certain seasons and that some individual storm events are repeatable from year-to-year. The majority of storms develop near the receding seasonal polar cap edge or along the corresponding polar hood boundaries in their respective hemispheres, but they also occur in the northern plains, the windward side of the large shield volcanoes, and in low laying regions such as Hellas, Argyre, and Chryse. The rarest of dust events are the "Great Storms" or "Global Events", of which only 6 (4 "planet encircling" and 2 "global") have been observed to date. With MOC we have observed that global dust events are not individual storms but are composed of a number of local and regional storms (sources) and that they do not signify climatic changes, but are only short-term perturbations to the general interannually repeatable Martian dust storm cycle.

Lunar and Planetary Science XXXVI, Part 20

NASA Technical Reports Server (NTRS)

2005-01-01

The topics include: 1) Virtual Reality Technology as a Tool to Enhance Collaboration Between Space Exploration and Public Outreach: The Case Using the Mars Exploration Rover Images; 2) Atmospheric Electron-induced X-Ray Spectrometer (AEXS) Instrument Development; 3) Impact of Low Thermal Conductivity Layers on the Bulk Conductivity of a Martian Crustal Column; 4) Impacting Classroom Teachers Through Long-Term Professional Development; 5) Oxygen, Ca, and Ti Isotopic Compositions of Hibonite-bearing Inclusions; 6) Phenomenological Excitation Functions of Xe Isotopes with Protons on Nuclei of Cs, La and Ce; 7) Double-Diffusive Convection and Other Modes of Salinity-modulated Heat and Material Transport in Europa s Ocean; 8) Slope Morphologies of the Hellas Mensae Constructs, Eastern Hellas Planitia, Mars; 9) Development of Polygonal Thermal Contraction Patterns in a South Polar Trough, Mars 3 Years of Observations; 10) Martian Relevance of Dehydration and Rehydration in the Mg-Sulfate System; 11) Formation of Martian Volcanic Provinces by Lower Mantle Flushing? 12) Can Glasses Help Us to Unravel the Origin of Barred Olivine Chondrules? 13) Loki Patera: A Magma Sea Story; 14) Compositions of Partly Altered Olivine and Replacement Serpentine in the CM2 Chondrite QUE93005; 15) Model of Light Scattering by Lunar Regolith at Moderate Phase Angles: New Results; 16) Radiation Resistance of a Silicone Polymer Grease Based Regolith Collector for the HERA Near-Earth Asteroid Sample Return Mission; 17) Analysis of the Tectonic Lineaments in the Ganiki Planitia (V14) Quadrangle, Venus; 18) Nanometer-sized Diamonds from AGB Stars; 19) Quantifying Exact Motions Along Lineaments on Europa; 20) Geometry of Thrust Faults Beneath Amenthes Rupes, Mars; 21) Mapping of the Physical Characteristics and Mineral Composition of a Superficial Layer of the Moon or Mars and Ultra-Violet Polarimetry from the Orbital Station; 22) Negative Searches for Evidence of Aqueous Alteration on Asteroid Surfaces; 23) What Processes Have Shaped Basalt Boulders on Earth and Mars? Studies of Feature Persistence Using Facet Mapping and Fractal Analysis; 24) The Popigai Fluidizites: Dense Water Inclusions in Lechatelierite; Evidence for Shock-generated Carbonate and Hydrous Silicate Melts; 25) Missing Xenon Problem and Climate of the Early Earth; and 26) More on Magnetic Spectra from Correlated Crustal Sources on Mars

Magnetometer Data Tests Models for the Origin of the Martian Crustal Dichotomy; Dichotomy Models Constrain Timing of Martian Magnetic Field

NASA Technical Reports Server (NTRS)

Gilmore, M. S.

1999-01-01

Measurements recently supplied by the MGS Magnetometer/Electron Reflectometer (MAG/ER) on MGS can be applied to test theories of the origin of the martian crustal dichotomy. Strong (+/- 1500 nT) magnetic anomalies are observed in the Martian crust. The observations can be summarized as follows: 1) strong crustal magnetic sources are generally confined to the southern highlands, although weaker (approx. 40 nT) anomalies were observed during close periapsis; 2) strong magnetic anomalies are absent in the vicinity of Hellas and Argyre; 3) the anomalies in the region 0 deg to 90 deg S, 120 deg to 240 deg west have a linear geometry, strike generally east west for 1000s km, and show several reversals. This latter point has led to the suggestion that some form of lateral plate tectonics may have been operative in the southern highlands of Mars. These observations have led previous workers to hypothesize that the magnetic anomalies were present prior to and were destroyed by the formation of Hellas and Argyre. As such large impacts are confined to the era of heavy bombardment, this places the time of formation of large magnetic anomalies prior to approx. 3.9 Ga. One obvious extension of this is that the northern lowlands lack significant anomalies because they were erased by impacts and/or the northern lowlands represent crust completely reheated above the Curie temperature. Preliminary observations of the distributions of the large crustal magnetic anomalies show that many of them extend continuously over the highland lowland boundary. This occurs particularly north of the boundary between 30 deg W and 270 deg W, corresponding to northern Arabia, but also occurs in southern Elysium (approx. 10 deg S, 200 deg) and the SW portion of Tharsis (approx. 15 deg S, 140 deg). This suggests that, in these areas, Noachian crust containing the greater than 3.9 Ga magnetic signature, lies beneath the northern highlands. This geometry can be used to test models for the formation of the martian crustal dichotomy. Additional information is contained in the original extended abstract.

Pluto is the new Mars!

NASA Technical Reports Server (NTRS)

Moore, Jeffrey M.; Mckinnon, William B.; Spencer, John R.; Howard, Alan D.; Grundy, William M.; Stern, S. Alan; Weaver, Harold A.; Young, Leslie A.; Ennico, Kimberly; Olkin, Cathy

2016-01-01

Data from NASA's New Horizons encounter with Pluto in July 2015 revealed an astoundingly complex world. The surface seen on the encounter hemisphere ranged in age from ancient to recent. A vast craterless plain of slowly convecting solid nitrogen resides in a deep primordial impact basin, reminiscent of young enigmatic deposits in Mars' Hellas basin. Like Mars, regions of Pluto are dominated by valleys, though the Pluto valleys are thought to be carved by nitrogen glaciers. Pluto has fretted terrain and halo craters. Pluto is cut by tectonics of several different ages. Like Mars, vast tracts on Pluto are mantled by dust and volatiles. Just as on Mars, Pluto has landscapes that systematically vary with latitude due to past and present seasonal (and mega-seasonal) effects on two major volatiles. On Mars, those volatiles are H2O and CO2; on Pluto they are CH4 and N2. Like Mars, some landscapes on Pluto defy easy explanation. In the Plutonian arctic there is a region of large (approx. 40 km across) deep (approx. 3-4 km) pits that probably could not be formed by sublimation, or any other single process, alone. Equally bizarre is the Bladed terrain, which is composed of fields of often roughly aligned blade-like ridges covering the flanks and crests of broad regional swells. Topping the unexpected are two large mounds approximately150 km across, approx. 5-6 km high, with great central depressions at their summits. The central depressions are almost as deep as the mounds are tall. These mounds have many of the characteristics of volcanic mountains seen on Mars and elsewhere in the inner solar system. Hypotheses for the formation of these Plutonian mounds so far all have challenges, principally revolving around the need for H2O ice to support their relief and the difficulty imagining mechanisms that would mobilize H2O. From the perspective of one year after the encounter, our appreciation of the extent of Pluto's diversity and complexity is quite reminiscent of the perspective the science community had of Mars, with similar quality data sets, soon after the early reconnaissance of that planet in the late 1960s and early 70s. So certainly in this sense, Pluto is the new Mars.

An Inversion of Gravity and Topography for Mantle and Crustal Structure on Mars

NASA Technical Reports Server (NTRS)

Kiefer, Walter S.; Bills, Bruce G.; Nerem, R. Steven

1996-01-01

Analysis of the gravity and topography of Mars presently provides our primary quantitative constraints on the internal structure of Mars. We present an inversion of the long-wavelength (harmonic degree less than or equal to 10) gravity and topography of Mars for lateral variations of mantle temperature and crustal thickness. Our formulation incorporates both viscous mantle flow (which most prior studies have neglected) and isostatically compensated density anomalies in the crust and lithosphere. Our nominal model has a 150-km-thick high-viscosity surface layer over an isoviscous mantle, with a core radius of 1840 km. It predicts lateral temperature variations of up to a few hundred degrees Kelvin relative to the mean mantle temperature, with high temperature under Tharsis and to a lesser extent under Elysium and cool temperatures elsewhere. Surprisingly, the model predicts crustal thinning beneath Tharsis. If correct, this implies that thinning of the crust by mantle shear stresses dominates over thickening of the crust by volcanism. The major impact basins (Hellas, Argyre, Isidis, Chryse, and Utopia) are regions of crustal thinning, as expected. Utopia is also predicted to be a region of hot mantle, which is hard to reconcile with the surface geology. An alternative model for Utopia treats it as a mascon basin. The Utopia gravity anomaly is consistent with the presence of a 1.2 to 1.6 km thick layer of uncompensated basalt, in good agreement with geologic arguments about the amount of volcanic fill in this area. The mantle thermal structure is the dominant contributor to the observed geoid in our inversion. The mantle also dominates the topography at the longest wavelengths, but shorter wavelengths (harmonic degrees greater than or equal to 4) are dominated by the crustal structure. Because of the uncertainty about the appropriate numerical values for some of the model's input parameters, we have examined the sensitivity of the model results to the planetary structural model (core radius and core and mantle densities), the mantle's viscosity stratification, and the mean crustal thickness. The model results are insensitive to the specific thickness or viscosity contrast of the high-viscosity surface layer and to the mean crustal thickness in the range 25 to 100 km. Models with a large core radius or with an upper mantle low-viscosity zone require implausibly large lateral variations in mantle temperature.

Formation and mantling ages of lobate debris aprons on Mars: Insights from categorized crater counts

NASA Astrophysics Data System (ADS)

Berman, Daniel C.; Crown, David A.; Joseph, Emily C. S.

2015-06-01

Lobate debris aprons in the Martian mid-latitudes offer important insights into the history of the Martian climate and the role of volatiles in Martian geologic activity. Here we present the results of counts of small impact craters, categorized by morphology, on debris aprons in the Deuteronilus Mensae region and the area east of Hellas basin. Mars Reconnaissance Orbiter (MRO) ConTeXt Camera (CTX) images were used to document crater populations on the apron surfaces. Each crater was assessed and categorized according to its morphological characteristics (fresh, degraded, or filled). Fresh and most degraded craters likely superpose recent mantling deposits, whereas filled craters contain mantling deposits and thus indicate a minimum formation age for the apron (i.e., the age since stabilization of the debris apron surface following some modification but prior to mantling). Size-frequency distributions (SFDs) were compiled using established methodologies and plotted to assess their fit to the isochrons. The range or ranges in crater diameter over which each distribution paralleled the isochrons was determined by visual inspection, and general age constraints were noted from SFDs for all craters on a given surface and from each morphological class. The diameter range of each SFD segment observed to parallel an isochron was then input into the Craterstats2 analysis tool to calculate specific age estimates. The aprons were assessed both individually and as regional populations, which improved interpretation of the results and demonstrated the value and limitations of both approaches. The categorized counts reveal three groups of ages: (a) filled impact craters at larger diameters (>~500 m) typically show the oldest ages, between ~300 Ma and 1 Ga, (b) smaller diameter filled and degraded craters reveal ages of resurfacing events between ~10 Ma and 300 Ma, and (c) fresh crater populations (<~100 m diameter) indicate mantling deposits of less than ~10 Ma in age. These results indicate that the lobate debris apron populations formed (or their surfaces became stable) in the Early to Middle Amazonian Epochs, and were subsequently subjected to complex degradation by erosion and sublimation and/or melting of contained ice, culminating in episodes of deposition of ice-rich mantles in the Late Amazonian Epoch.

The structure and evolution of ancient impact basins on Mars

NASA Technical Reports Server (NTRS)

Schultz, P. H.; Schultz, R. A.; Rogers, J.

1982-01-01

It is pointed out that characteristic styles of degradation and modification of obvious Martian basins make it possible to recognize more subtle expressions. This approach is seen as providing not only additional basins to the existing inventory but also fundamental clues for initial impact basin structure and stratigraphy. It also reveals the long-lasting influence of basin formation on the crust of Mars in spite of extensive erosion and resurfacing. Consideration is given to five clear examples of modified impact basins, and regions around each that have undergone similar processes (fracturing, collapse, channeling) are delineated. These processes among the different basins are then compared, and similar zones of modification are correlated with concentric basin rings. Consideration is then given to the implications of these observations for current models of basin formation and to the role of impact basins in controlling regional tectonics. The results indicate that large multiring impact scars leave a major but sometimes subtle imprint on the geologic structure of stable crustal regions on Mars.

Asymmetric Distribution of Lunar Impact Basins Caused by Variations in Target Properties

NASA Technical Reports Server (NTRS)

Miljkovic, Katarina; Wieczorek, Mark A.; Collins, Gareth S.; Laneuville, Matthieu; Neumann, Gregory A.; Melosh, H. Jay; Solomon, Sean C.; Phillips, Roger J.; Smith, David E.; Zuber, Maria T.

2014-01-01

Maps of crustal thickness derived from NASA's Gravity Recovery and Interior Laboratory (GRAIL) mission revealed more large impact basins on the nearside hemisphere of the Moon than on its farside. The enrichment in heat-producing elements and prolonged volcanic activity on the lunar nearside hemisphere indicate that the temperature of the nearside crust and upper mantle was hotter than that of the farside at the time of basin formation. Using the iSALE-2D hydrocode to model impact basin formation, we found that impacts on the hotter nearside would have formed basins up to two times larger than similar impacts on the cooler farside hemisphere. The size distribution of lunar impact basins is thus not representative of the earliest inner Solar system impact bombardment.

Supplemental Information For: Asymmetric Distribution of Lunar Impact Basins Caused by Variations in Target Properties

NASA Technical Reports Server (NTRS)

Miljkovic, Katarina; Wieczorek, Mark; Collins, Gareth S.; Laneuville, Matthieu; Neumann, Gregory A.; Melosh, H. Jay; Solomon, Sean C.; Phillips, Roger J.; Smith, David E.; Zuber, Maria T.

2014-01-01

Maps of crustal thickness derived from NASA's Gravity Recovery and Interior Laboratory (GRAIL) mission revealed more large impact basins on the nearside hemisphere of the Moon than on its farside. The enrichment in heat-producing elements and prolonged volcanic activity on the lunar nearside hemisphere indicate that the temperature of the nearside crust and uppermantle was hotter than that of the farside at the time of basin formation. Using the iSALE-2D hydrocode to model impact basin formation, we found that impacts on the hotter nearside would have formed basins up to two times larger than similar impacts on the cooler farside hemisphere. The size distribution of lunar impact basins is thus not representative of the earliest inner Solar system impact bombardment

Signs of Landscape Modifications at Martian Crater

NASA Technical Reports Server (NTRS)

2009-01-01

[figure removed for brevity, see original site] Click on the image for larger version

The lower portion of this image from the Thermal Emission Imaging System camera (THEMIS) on NASA's Mars Odyssey orbiter shows a crater about 16 kilometers (10 miles) in diameter with features studied as evidence of deposition or erosion. The crater is centered at 40.32 degrees south latitude and 132.5 degrees east longitude, in the eastern portion of the Hellas basin on Mars. It has gullies and arcuate ridges on its north, pole-facing interior wall. This crater is in the center of a larger (60-kilometer or 37-mile diameter) crater with lobate flows on its north, interior wall. The image, number V07798008 in the THEMIS catalog, covers a swath of ground 17.4 kilometers (10.8 miles) wide.

NASA's Jet Propulsion Laboratory manages the Mars Odyssey mission for NASA's Office of Space Science. THEMIS was developed by Arizona State University in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is led by Dr. Philip Christensen at Arizona State University. Lockheed Martin Astronautics, Denver, is the prime contractor for the Odyssey project, and developed and built the orbiter. Mission operations are conducted jointly from Lockheed Martin and from JPL, a division of the California Institute of Technology in Pasadena.

"Hella Ghetto!": (Dis)Locating Race and Class Consciousness in Youth Discourses of Ghetto Spaces, Subjects and Schools

ERIC Educational Resources Information Center

Sung, Kenzo K.

2015-01-01

Based on analysis of interviews conducted during 2008-2009 in Oakland, California, this article examines how narratives of inner-city youth reinforce and destabilize mainstream conceptions of "ghetto." The article demonstrates that inner-city youth discourses regarding "ghetto" spaces, subjects and schools often exemplify a…

Nature of the South Pole on Mars Determined by Topographic Forcing of Atmosphere Dynamics

NASA Technical Reports Server (NTRS)

Colaprete, A.; Barnes, Jeffrey R.; Haberle, Robert M.; Hollingsworth, Jeffery L.; Kieffer, Hugh H.; Titus, Timothy N.

2005-01-01

Introduction: The observed Springtime (Ls approx. 200) surface albedo in the Martian southern polar region is shown in Figure 1. In general, the hemisphere west of Hellas is marked by relatively high values of surface albedo. In contrast, the hemisphere east of Hellas contains extensive regions of very low surface albedo. One of the brightest features within the western hemisphere is the South Pole Residual Cap (SPRC). The dark region, which dominates the eastern hemisphere, is the "Cryptic" region[1]. The nature of the SPRC has been the source of considerable debate since its identification as CO2 ice by the Viking spacecraft. Two fundamental questions still exist regarding the SPRC s formation, location and stability. First, why is the SPRC offset from the geographic pole? There are no local topographic features or surface properties that can account for the offset in the SPRC. Second, does the SPRC represent a large or a small reservoir of CO2? If the former, then it could possibly buffer the surface pressure. If the latter, then the SPRC may not survive every year.

Pulling Marbles from a Bag: Deducing the Regional Impact History of the SPA Basin from Impact-Melt Rocks

NASA Technical Reports Server (NTRS)

Cohen, Barbara A.; Coker, Robert F.

2010-01-01

The South Pole Aitken (SPA) basin is the stratigraphically oldest identifiable lunar basin and is therefore one of the most important targets for absolute age-dating to help understand whether ancient lunar bombardment history smoothly declined or was punctuated by a cataclysm. A feasible near-term approach to this problem is to robotically collect a sample from near the center of the basin, where vertical and lateral mixing provided by post-basin impacts ensures that such a sample will be composed of small rock fragments from SPA itself, from local impact craters, and from faraway giant basins. The range of ages, intermediate spikes in the age distribution, and the oldest ages are all part of the definition of the absolute age and impact history recorded within the SPA basin.

Evolution of the Rembrandt impact basin on Mercury.

PubMed

Watters, Thomas R; Head, James W; Solomon, Sean C; Robinson, Mark S; Chapman, Clark R; Denevi, Brett W; Fassett, Caleb I; Murchie, Scott L; Strom, Robert G

2009-05-01

MESSENGER's second Mercury flyby revealed a ~715-kilometer-diameter impact basin, the second-largest well-preserved basin-scale impact structure known on the planet. The Rembrandt basin is comparable in age to the Caloris basin, is partially flooded by volcanic plains, and displays a unique wheel-and-spoke-like pattern of basin-radial and basin-concentric wrinkle ridges and graben. Stratigraphic relations indicate a multistaged infilling and deformational history involving successive or overlapping phases of contractional and extensional deformation. The youngest deformation of the basin involved the formation of a approximately 1000-kilometer-long lobate scarp, a product of the global cooling and contraction of Mercury.

Distribution, Statistics, and Resurfacing of Large Impact Basins on Mercury

NASA Technical Reports Server (NTRS)

Fassett, Caleb I.; Head, James W.; Baker, David M. H.; Chapman, Clark R.; Murchie, Scott L.; Neumann, Gregory A.; Oberst, Juergen; Prockter, Louise M.; Smith, David E.; Solomon, Sean C.;

Meteorological predictions for Mars 2020 Exploration Rover high-priority landing sites throug MRAMS Mesoscale Modeling

NASA Astrophysics Data System (ADS)

Pla-García, Jorge; Rafkin, Scot C. R.

2015-04-01

The Mars Regional Atmospheric Modeling System (MRAMS) is used to predict meteorological conditions that are likely to be encountered by the Mars 2020 Exploration Rover at several proposed landing sites during entry, descent, and landing (EDL). The meteorology during the EDL window at most of the sites is dynamic. The intense heating of the lower atmosphere drives intense thermals and mesoscale thermal circulations. Moderate mean winds, wind shear, turbulence, and vertical air currents associated with convection are present and potentially hazardous to EDL [1]. Nine areas with specific high-priority landing ellipses of the 2020 Rover, are investigated: NE Syrtis, Nili Fossae, Nili Fossae Carbonates, Jezero Crater Delta, Holden Crater, McLaughlin Crater, Southwest Melas Basin, Mawrth Vallis and East Margaritifer Chloride. MRAMS was applied to the landing site regions using nested grids with a spacing of 330 meters on the innermost grid that is centered over each landing site. MRAMS is ideally suited for this investigation; the model is explicitly designed to simulate Mars' atmospheric thermal circulations at the mesoscale and smaller with realistic, high-resolution surface properties [2, 3]. Horizontal wind speeds, both vertical profiles and vertical cross-sections wind speeds, are studied. For some landing sites simulations, two example configurations -including and not including Hellas basin in the mother domain- were generated, in order to study how the basin affects the innermost grids circulations. Afternoon circulations at all sites pose some risk entry, descent, and landing. Most of the atmospheric hazards are not evident in current observational data and general circulation model simulations and can only be ascertained through mesoscale modeling of the region. Decide where to go first and then design a system that can tolerate the environment would greatly minimize risk. References: [1] Rafkin, S. C. R., and T. I. Michaels (2003), J. Geophys. Res., 108(E12), 8091. [2] Rafkin, S. C. R., R. M. Haberle, and T. I. Michaels (2001), Icarus, 151, 228-256.
[3] Rafkin, S. C. R., M. R. V. Sta. Maria, and T. I. Michaels (2002), Nature, 419, 697-699.

Friction melt distribution in a multi-ring impact basin.

PubMed

Spray, J G; Thompson, L M

1995-01-12

It is generally accepted that multi-ring basins are the consequence of very large impacts, but the mechanism by which they form is still a matter of contention. Most of what is currently known about multi-ring basins is based on remote studies of the Moon and, to a lesser extent, Mars and Mercury. But at least two multi-ring impact basins have been recognized on Earth--the Sudbury (Canada) and Vredefort (South Africa) impact structures--providing an opportunity to study their properties directly. Here we describe the distribution of friction melt (pseudotachylyte) in the floor of the Sudbury impact basin. Although the veins and dykes of pseudotachylyte decrease in both thickness and frequency of occurrence towards the basin periphery, the greatest volumes of friction melt appear to define four rings around the central impact melt sheet. Field evidence indicates that the rings originated as zones of large displacement, which facilitated localized frictional melting of the basin floor during the modification (collapse) stage of the cratering process. By analogy, we argue that the rings of other multi-ring impact basins are also likely to be the remnants of such large-displacement fault zones.

Possible Layers on Floor of Suzhi Crater

NASA Image and Video Library

2016-12-14

This image shows the floor of Suzhi Crater, an approximately 25-kilometer diameter impact crater located northeast of Hellas Planitia. The crater floor is mostly covered by dark-toned deposits; however some patches of the underlying light-toned bedrock are now exposed, like in this Context Camera image. This enhanced-color infrared image shows a close up of the exposed bedrock on the floor of the crater. Here we can see the lighter-toned bedrock partially covered up by darker-toned bedrock and a few wind-blown bedforms. The lighter-toned bedrock appears to lie over yet another type of bedrock in our image, which appears to be yellowish and heavily fractured. What complex tale of Martian geologic and climate history might these rocks tell us if we were able to sample them in person? Perhaps, one day we'll know. The University of Arizona, Tucson, operates HiRISE, which was http://photojournal.jpl.nasa.gov/catalog/PIA21273

77 FR 18897 - Greek Independence Day: A National Day of Celebration of Greek and American Democracy, 2012

Federal Register 2010, 2011, 2012, 2013, 2014

2012-03-28

... Independence Day: A National Day of Celebration of Greek and American Democracy, 2012 By the President of the United States of America A Proclamation Two hundred and thirty-six years ago, a new American Nation was... ancient Hellas, where Greeks brought forth the world's first democracy and kindled a philosophical...

Orientale Impact Basin: Topographic Characterization from Lunar Orbiter Laser Altimeter (LOLA) Data and Implications for Models of Basin Formation and Filling

NASA Astrophysics Data System (ADS)

Head, James; Smith, David; Zuber, Maria; Neumann, Gregory; Fassett, Caleb; Whitten, Jennifer; Garrick-Bethell, Ian

2010-05-01

The 920 km diameter Orientale basin is the youngest and most well-preserved large multi-ringed impact basin on the Moon; it has not been significantly filled with mare basalts, as have other lunar impact basins, and thus the basin interior deposits and ring structures are very well-exposed and provide major insight into the formation and evolution of planetary multi-ringed impact basins. We report here on the acquisition of new altimetry data for the Orientale basin from the Lunar Orbiter Laser Altimeter (LOLA) on board the Lunar Reconnaissance Orbiter. Pre-basin structure had a major effect on the formation of Orientale; we have mapped dozens of impact craters underlying both the Orientale ejecta (Hevelius Formation-HF) and the unit between the basin rim (Cordillera ring-CR) and the Outer Rook ring (OR) (known as the Montes Rook Formation-MRF), ranging up in size to the 630 km diameter Mendel-Rydberg basin just to the south of Orientale; this crater-basin topography has influenced the topographic development of the basin rim (CR), sometimes causing the basin rim to lie at a topographically lower level than the inner basin rings (OR and Inner Rook-IR). In contrast to some previous interpretations, the distribution of these features supports the interpretation that the OR ring is the closest approximation to the basin excavation cavity. The total basin interior topography is highly variable and typically ranges ~6-7 km below the surrounding pre-basin surface, with significant variations in different quadrants. The inner basin depression is about 2-4 km deep below the IR plateau. These data aid in the understanding of the transition from peak-ring to multi-ringed basins and permit the quantitative assessment of post-basin-formation thermal response to impact energy input and uplifted isotherms. The Maunder Formation (MF) consists of smooth plains (on the inner basin depression walls and floor) and corrugated deposits (on the IR plateau); also observed are depressions interpreted to be due to local drainage, and cracks related to cooling and solidification. This configuration supports the interpretation that the MF consists of different facies of impact melt. The location of vents, the altimetric distribution, and the slopes of mare basalts of different ages permit an assessment of basin controls on mare basalt emplacement. The inner depression is floored by tilted mare basalt deposits surrounding a central pre-mare high of several hundred meters elevation and deformed by wrinkle ridges with similar topographic heights; these data permit the assessment of basin loading by mare basalts and ongoing basin thermal evolution. LOLA data for the Orientale basin thus provide new insight into models of multi-ring basin formation, important information on their early thermal evolution, and new data on the initial stages of mare basalt flooding of multi-ringed basins.

Impact basins on Venus and some interplanetary comparisons

NASA Technical Reports Server (NTRS)

Spudis, Paul D.; Sharpton, Virgil L.

1993-01-01

Impact is one of the many processes that have shaped the surface of Venus. The largest impact craters, basins, are important features affecting the evolution of the terrestrial planets. Because Venus has an atmosphere, a gravity similar to Earth's, and a surface target with a high geothermal gradient, venusian basins provide an important comparative set of data to test our ideas about basin-forming impacts and their geological effects on the evolution of the crusts of the terrestrial planets.

New Classification of Impact Basins and Its Implications for Basin Evolution on the Moon

NASA Astrophysics Data System (ADS)

Ji, J.; Liu, J.; Guo, D.

2016-12-01

Large impact basins, the comprehensive results of internal and external dynamic geological processes, are the principal topographic features on the Moon. Study on evolution of those large impact basins provides important clues for understanding early history of the Moon. However, to classify the impact basins before anyone can link their characteristics to basin evolution, discrepancies occur among different classification systems, of which some did not to consider the effect of filled basalt [1] or some did not to consider the category of non-mascon basins [2, 3]. In order to clarify the ambiguous basin types caused by different classifications, we re-examined impact basins ≥ 200 km in diameter (66 in total; excluding SPA basin) using the GRAIL geophysical data, LRO DEM data and LP geochemical data from NASA Planetary Data System. We chose two major category labels: mascon or not [1, 2, 3] and the basin floor is covered by basalt/basaltic materials or not [4, 5]; plus, we considered topographic signatures as the clue of timescale. As a result, the 66 impact basins were classified into four categories: Type I (20), mascon basins with basalt or basaltic materials and most of them show well-preserved topography signature; Type II (28), mascon basins without basalt or basaltic materials, most of them are located on the farside with preserved topography signature; Type III (11), non-mascon basins with basalt or basaltic materials, most basins of this type are dated as Pre-Nectarian except for Van de Graaff basin and showing severely degraded topography; Type IV (6), non-mascon basins without basalt or basaltic materials, all basins of this type are dated as Pre-Nectarian with severely degraded topography. This new classification scheme can be easily applied to various lunar basins and help us to locate important information about early environment or thermal state of the Moon by comparison study of regional geological evolution of different basin types. References [1] N. Noriyuki N et al., 2009, Science 323(5916) . [2] P. S. Mohit and R. J. Phillips, 2006, J. Geophys. Res. 111(E12001). [3] A. J. Dombard et al., 2013, Geophys. Res. Lett. 40(1).[4] J. Arkani-Hamed, 1998, J. Geophys. Res. 103(E2).[5] G. A. Neumann et al., 1996, J. Geophys. Res 101(E7).

Orientale Impact Basin and Vicinity: Topographic Characterization from Lunar Orbiter Laser Altimeter (LOLA) Data

NASA Astrophysics Data System (ADS)

Head, J. W.; Smith, D. E.; Zuber, M. T.; Neumann, G. A.; Fassett, C.; Mazarico, E.; Torrence, M. H.; Dickson, J.

2009-12-01

The 920 km diameter Orientale basin is the youngest and most well-preserved large multi-ringed impact basin on the Moon; it has not been significantly filled with mare basalts, as have other lunar impact basins, and thus the basin interior deposits and ring structures are very well-exposed and provide major insight into the formation and evolution of planetary multi-ringed impact basins. We report here on the acquisition of new altimetry data for the Orientale basin from the Lunar Orbiter Laser Altimeter (LOLA) on board the Lunar Reconnaissance Orbiter. Pre-basin structure had a major effect on the formation of Orientale; we have mapped dozens of impact craters underlying both the Orientale ejecta (Hevelius Formation-HF) and the unit between the basin rim (Cordillera ring-CR) and the Outer Rook ring (OR) (known as the Montes Rook Formation-MRF), ranging up in size to the Mendel-Rydberg basin just to the south of Orientale; this crater-basin topography has influenced the topographic development of the basin rim (CR), sometimes causing the basin rim to lie at a topographically lower level than the inner basin rings (OR and Inner Rook-IR). In contrast to some previous interpretations, the distribution of these features supports the interpretation that the OR ring is the closest approximation to the basin excavation cavity. The total basin interior topography is highly variable and typically ranges ~6-7 km below the surrounding pre-basin surface, with significant variations in different quadrants. The inner basin depression is about 2-4 km deep below the IR plateau and these data permit the quantitative assessment of post-basin-formation thermal response to impact energy input and uplifted isotherms. The Maunder Formation (MF) consists of smooth plains (on the inner basin depression walls and floor) and corrugated deposits (on the IR plateau); this topographic configuration supports the interpretation that the MF consists of different facies of impact melt. The inner depression is floored by tilted mare basalt deposits surrounding a central pre-mare high of several hundred meters elevation and the mare is deformed by wrinkle ridges with similar topographic heights; these data permit the assessment of basin loading by mare basalts and ongoing basin thermal evolution. The depth of the 55 km diameter post-Orientale Maunder crater, located at the edge of the inner depression, is in excess of 3 km; this depth permits the quantitative assessment of the nature of the deeper sub-Orientale material sampled by the crater. New LOLA data show that the pre-Orientale Mendel-Rydberg basin just to the south may be larger, younger, fresher, and more comparable in size to Orientale than previously suspected.

The large impact process inferred from the geology of lunar multiring basins

NASA Technical Reports Server (NTRS)

Spudis, Paul D.

1992-01-01

The nature of the impact process has been inferred through the study of the geology of a wide variety of impact crater types and sizes. Some of the largest craters known are the multiring basins found in ancient terrains of the terrestrial planets. Of these features, those found on the Moon possess the most extensive and diverse data coverage, including morphological, geochemical, geophysical, and sample data. The study of the geology of lunar basins over the past 10 years has given us a rudimentary understanding of how these large structures have formed and evolved. The topics covered include basin morphology, basin ejecta, basin excavation, and basin ring formation.

Ancient Multiring Basins on the Moon Revealed by Clementine Laser Altimetry

NASA Astrophysics Data System (ADS)

Spudis, Paul D.; Reisse, Robert A.; Gillis, Jeffrey J.

1994-12-01

Analysis of laser altimetry data from Clementine has confirmed and extended our knowledge of nearly obliterated multiring basins on the moon. These basins were formed during the early bombardment phase of lunar history, have been filled to varying degrees by mare lavas and regional ejecta blankets, and have been degraded by the superposition of large impact craters. The Mendel-Rydberg Basin, a degraded three-ring feature over 600 kilometers in diameter on the lunar western limb, is about 6 kilometers deep from rim to floor, only slightly less deep than the nearby younger and much better preserved Orientale Basin (8 kilometers deep). The South Pole-Aitken Basin, the oldest discernible impact feature on the moon, is revealed as a basin 2500 kilometers in diameter with an average depth of more than 13 kilometers, rim crest to floor. This feature is the largest, deepest impact crater yet discovered in the solar system. Several additional depressions seen in the data may represent previously unmapped ancient impact basins.

H.E.L.L.A.: Collective "Testimonio" That Speak to the Healing, Empowerment, Love, Liberation, and Action Embodied by Social Justice Educators of Color

ERIC Educational Resources Information Center

Pour-Khorshid, Farima

2016-01-01

This author utilizes collective "testimonio" (Sánchez, 2009) as a process for "homemade theory" making or what Anzaldúa and Keating (2000) called "conocimientos." This collective "testimonio" brings together the stories and experiences of three educators of color within a California grassroots social justice…

Correlation of lunar far-side magnetized regions with ringed impact basins

USGS Publications Warehouse

Anderson, K.A.; Wilhelms, D.E.

1979-01-01

By the method of electron reflection, we have identified seven well-defined magnetized regions in the equatorial belt of the lunar far side sampled by the Apollo 16 Particles and Fields subsatellite. Most of these surface magnetic fields lie within one basin radius from the rim of a ringed impact basin, where thick deposits of basin ejecta are observed or inferred. The strongest of the seven magnetic features is linear, at least 250 km long, and radial to the Freundlich-Sharonov basin. The apparent correlation with basin ejecta suggests some form of impact origin for the observed permanently magnetized regions. ?? 1979.

Morphologic classes of impact basins on Venus

NASA Technical Reports Server (NTRS)

Wood, Charles A.; Tam, Wesley

1993-01-01

An independent survey of 60% of Venus has resulted in the detection of 35 impact basins and associated transitional rings. Contrary to previous studies central peak basins have been identified, as well as peak ring basins. But no unambiguous multi-ring basins have been detected. A new class of crateriform - expanded peak structure - has been noticed, which is transitional in diameter, but apparently not in structure, between central peak and peak ring basins.

Map of Martian Potassium at Mid-Latitudes

NASA Technical Reports Server (NTRS)

2003-01-01

This gamma ray spectrometer map of the mid-latitude region of Mars is based on gamma-rays from the element potassium. Potassium, having the chemical symbol K, is a naturally radioactive element and is a minor constituent of rocks on the surface of both Mars and Earth. The region of highest potassium content, shown in red, is concentrated in the northern part of Acidalia Planitia (centered near 55 degrees N, -30 degrees). Several areas of low potassium content, shown in blue, are distributed across the mid-latitudes, with two significant low concentrations, one associated with the Hellas Basin (centered near 35 degrees S, 70 degrees) and the other lying southeast of Elysium Mons (centered near 10 degrees N, 160 degrees). Contours of constant surface elevation are also shown. The long continuous line running from east to west marks the approximate separation of the younger lowlands in the north from the older highlands in the south.

NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The gamma ray spectrometer was provided by the University of Arizona, Tucson. Lockheed Martin Astronautics, Denver, is the prime contractor for the project, and developed and built the orbiter. Mission operations are conducted jointly from Lockheed Martin and from JPL, a division of the California Institute of Technology in Pasadena.

Distribution of Large Visible and Buried Impact Basins on Mars: Comparison with Free-Air Gravity, Crustal Thickness and Magnetization Models

NASA Technical Reports Server (NTRS)

Frey, H. V.

2004-01-01

A comparison of the distribution of visible and buried impact basins (Quasi-Circular Depressions or QCDs) on Mars > 200 km in diameter with free air gravity, crustal thickness and magnetization models shows some QCDs have coincident gravity anomalies but most do not. Very few QCDs have closely coincident magnetization anomalies, and only the oldest of the very large impact basins have strong magnetic anomalies within their main rings. Crustal thickness data show a large number of Circular Thinned Areas (CTAs). Some of these correspond to known impact basins, while others may represent buried impact basins not always recognized as QCDs in topography data alone. If true, the buried lowlands may be even older than we have previously estimated.

Impact-Basin Formation on Mercury: Current Observations and Outstanding Questions

NASA Astrophysics Data System (ADS)

Baker, D. M. H.; Head, J. W.; Fassett, C. I.

2018-05-01

Mercury provides an important laboratory for understanding impact-basin formation on planetary bodies. MESSENGER observations improved our understanding, but much is still unknown about the formation and evolution of basin features.

The Formation of Lunar Impact Basins: Observational Constraints from LRO Datasets and Comparisons with Models

NASA Astrophysics Data System (ADS)

Baker, D. M. H.; Head, J. W., III

2016-12-01

Impact basins provide windows into the subsurface and through time on a planetary body. However, meaningful geologic interpretations rely on a detailed understanding of their formation and the origin of basin materials. Data from the Lunar Reconnaissance Orbiter (LRO) have been critical to advancing our understanding of the formation of impact basins. We present a number of recent observations, including measurements of basin morphometry, mineralogy, and gravity anomalies, which provide a framework for constraining current formation models. Image data from the LRO Wide Angle Camera (WAC) and altimetry data from the Lunar Orbiter Laser Altimeter (LOLA) were used to refine the recognition of both fresh and degraded impact basins, including their ring structures. Analyses of gravity anomalies from the GRAIL mission show that mantle uplifts confined within the inner basin rings are characteristics that basins acquire from the onset. We used LOLA data to also make new measurements of basin morphometry. Small basins possessing two concentric rings ("peak-ring basins") have unique topographic signatures, consisting of inner depressions bounded by a peak ring and a higher annulus that grades to steeper wall material. LRO Narrow Angle Camera (NAC) images and Diviner rock abundance maps were used to identify boulder-rich outcrops in basin rings, which focused mineralogical analyses using Moon Mineralogy Mapper hyperspectral data. Crystalline plagioclase and candidate shock plagioclase outcrops were found to be abundant within basins of all sizes. These observations combined with crater scaling laws and lunar crustal thickness constrain the depth of origin of basin peak rings to be near the maximum depth of excavation. Comparisons between iSALE numerical models and observations show important consistencies and inconsistencies that can help to refine current models. In particular, improvements in the match between observed and modeled morphometry of craters transitional between complex craters with central peaks and peak-ring basins are needed. Models of the predicted gravity signature for a range of basin sizes could also benefit from additional comparisons with those observed. This work also provides a framework for understanding the degraded impact-basin record on Earth, including the Chicxulub basin.

Morphology and Distribution of Volcanic Vents in the Orientale Basin from Chandrayaan-1 Moon Mineralogy Mapper (M3) Data

NASA Technical Reports Server (NTRS)

Head, James; Pieters, C.; Staid, M.; Mustard, J.; Taylor, L.; McCord, T.; Isaacson, P.; Klima, R.; Petro, N.; Clark, R.;

Compositional evidence for an impact origin of the Moon's Procellarum basin

NASA Astrophysics Data System (ADS)

Nakamura, Ryosuke; Yamamoto, Satoru; Matsunaga, Tsuneo; Ishihara, Yoshiaki; Morota, Tomokatsu; Hiroi, Takahiro; Takeda, Hiroshi; Ogawa, Yoshiko; Yokota, Yasuhiro; Hirata, Naru; Ohtake, Makiko; Saiki, Kazuto

2012-11-01

The asymmetry between the nearside and farside of the Moon is evident in the distribution of mare basalt, crustal thickness and concentrations of radioactive elements, but its origin remains controversial. According to one attractive scenario, a gigantic impact early in the Moon's history produced the observed dichotomy; the putative 3,000-km-diameter Procellarum basin has been suggested to be a relic of this ancient impact. Low-calcium pyroxene can be formed during an impact by melting a mixture of crust and mantle materials or by excavating differentiated cumulates from the lunar magma ocean. Therefore, the association of low-calcium pyroxene with a lunar basin could indicate an impact origin. Here we use spectral mapping data from KAGUYA/SELENE (ref. ) to show that low-calcium pyroxene is concentrated around two established impact structures, the South Pole-Aitken and Imbrium basins. In addition, we detect a high concentration of low-calcium pyroxene at Procellarum, which supports an impact origin of the ancient basin. We propose that, in forming the largest known basin on the Moon, the impact excavated the nearside's primary feldspathic crust, which derived from the lunar magma ocean. A secondary feldspathic crust would have later recrystallized from the sea of impact melt, leading to two distinct sides of the Moon.

Formation of South Pole-Aitken Basin as the Result of an Oblique Impact: Implications for Melt Volume and Source of Exposed Materials

NASA Technical Reports Server (NTRS)

Petro, N. E.

2012-01-01

The South Pole-Aitken Basin (SPA) is the largest, deepest, and oldest identified basin on the Moon and contains surfaces that are unique due to their age, composition, and depth of origin in the lunar crust [1-3] (Figure 1). SPA has been a target of interest as an area for robotic sample return in order to determine the age of the basin and the composition and origin of its interior [3-6]. As part of the investigation into the origin of SPA materials there have been several efforts to estimate the likely provenance of regolith material in central SPA [5, 6]. These model estimates suggest that, despite the formation of basins and craters following SPA, the regolith within SPA is dominated by locally derived material. An assumption inherent in these models has been that the locally derived material is primarily SPA impact-melt as opposed to local basement material (e.g. unmelted lower crust). However, the definitive identification of SPA derived impact melt on the basin floor, either by remote sensing [2, 7] or via photogeology [8] is extremely difficult due to the number of subsequent impacts and volcanic activity [3, 4]. In order to identify where SPA produced impact melt may be located, it is important to constrain both how much melt would have been produced in a basin forming impact and the likely source of such melted material. Models of crater and basin formation [9, 10] present clear rationale for estimating the possible volumes and sources of impact melt produced during SPA formation. However, if SPA formed as the result of an oblique impact [11, 12], the volume and depth of origin of melted material could be distinct from similar material in a vertical impact [13].

Ice-Ridge Pile Up and the Genesis of Martian "Shorelines"

NASA Technical Reports Server (NTRS)

Barnhart, C. J.; Tulaczyk, S.; Asphaug, E.; Kraal, E. R.; Moore, J.

2005-01-01

Unique geomorphologic features such as basin terraces exhibiting topographic continuity have been found within several Martian craters as shown in Viking, MOC, and THEMIS images. These features, showing similarity to terrestrial shorelines, have been mapped and cataloged with significant effort [1]. Currently, open wave action on the surface of paleolakes has been hypothesized as the geomorphologic agent responsible for the generation of these features [2]. As consequence, feature interpretations, including shorelines, wave-cut benches, and bars are, befittingly, lacustrine. Because such interpretations and their formation mechanisms have profound implications for the climate and potential biological history of Mars, confidence is crucial. The insight acquired through linked quantitative modeling of geomorphologic agents and processes is key to accurately interpreting these features. In this vein, recent studies [3,4] involving the water wave energy in theoretical open water basins on Mars show minimal erosional effects due to water waves under Martian conditions. Consequently, sub-glacial lake flattens the surface, produces a local velocity increase over the lake, and creates a deviation of the ice flow from the main flow direction [11]. These consequences of ice flow are observed at Lake Vostok, Antarctica an excellent Martian analogue [11]. Martian observations include reticulate terrain exhibiting sharp inter-connected ridges speculated to reflect the deposition and reworking of ice blocks at the periphery of ice-covered lakes throughout Hellas [12]. Our model determines to what extent ice, a terrestrial geomorphologic agent, can alter the Martian landscape. Method: We study the evolution of crater ice plugs as the formation mechanism of surface features frequently identified as shorelines. In particular, we perform model integrations involving parameters such as ice slope and purity, atmospheric pressure and temperature, crater shape and composition, and an energy balance between solar flux, geothermal flux, latent heat, and ablation. Our ultimate goal is to understand how an intracrater ice plug could create the observed shoreline features and how these

Maps of Structured Aerosol Activity During the MY 25 Planet-encircling Dust Storm on Mars

NASA Astrophysics Data System (ADS)

Noble, J.; Wilson, R. J.; Cantor, B. A.; Kahre, M. A.; Hollingsworth, J. L.; Bridger, A. F. C.; Haberle, R. M.; Barnes, J.

2016-12-01

We have produced a sequence of 42 global maps from Ls=165.1-187.7° that delimit the areal extent of structured aerosol activity based on a synthesis of Mars Global Surveyor (MGS) data, including Mars Orbiter Camera (MOC) daily global maps (DGMs) and wide angle imagery, Thermal Emission Spectrometer (TES) dust and H2O ice opacity, and Mars general circulation model (MGCM) derived dust opacity. The primary motivation of this work is to examine the temporal and spatial relationship between dust storms observed by MOC and baroclinic eddies inferred from Fast Fourier Synoptic Mapping (FFSM) of TES temperatures in order to study the initiation and evolution of Mars year (MY) 25 planet-encircling dust storm (PDS) precursor phase dust storms. A secondary motivation is to provide improved input to MGCM simulations. Assuming that structured dust storms indicate active dust lifting, these maps allow us to define potential dust lifting regions. This work has two implications for martian atmospheric science. First, integration of MGS data has enabled us to develop improved quantitative and qualitative descriptions of storm evolution that may be used to constrain estimates of dust lifting regions, horizontal dust distribution, and to infer associated circulations. Second, we believe that these maps provide better bases and constraints for modeling storm initiation. Based on our analysis of these MGS data, we propose the following working hypothesis to explain the dynamical processes responsible for PDS initiation and expansion. Six eastward-traveling transient baroclinic eddies triggered the MY 25 precursor storms in Hellas during Ls=176.2-184.6° due to the enhanced dust lifting associated with their low-level wind and stress fields. This was followed by a seventh eddy that contributed to expansion on Ls=186.3°. Increased opacity and temperatures from dust lifting associated with the first three eddies enhanced thermal tides which supported further storm initiation and expansion out of Hellas. Constructive interference of eddies and other circulation components including sublimation flow, anabatic winds (daytime upslope), and diurnal tides may have contributed to storm onset in, and expansion out of Hellas.

Permo-Carboniferous sedimentary basins related to the distribution of planetary cryptoblemes

USGS Publications Warehouse

Windolph, J.F.

1997-01-01

Massive/high velocity solar, galactic, and cosmic debris impacting the Earths surface may account for the enormous energy required for the formation of Permo-Carboniferous sedimentary basins and related mountain building orogenies. Analysis of satellite immagry, sea floor sonar, geophysical data, and geotectonic fabrics show a strong correlation throughout geologic time between sedimentary basin origin and planetary cryptoblemes. Cryptoblemes are subtile, multi-ringed, radial centric impact shock signatures covering the entire terrestrial surface and ocean floors, having a geometry and distribution strikingly similar to the surfaces of the lunar planetary bodies in the solar system. Investigations of Permo-Carboniferous basins show an intensely overprinted pattern of cryptoblemes coinciding with partial obliteration and elliptical compression of pre-existing basins and accompanying shock patterns. Large distorted cryptoblemes may incorporate thin skin deformation, localized sediment diagenesis, regional metamorphism, and juxtaposed exotic terrains. These data, related to basin morphogenic symmetry, suggest that large episodic impact events are the primary cause of tectonogenic features, geologic boundary formation and mass extinction episodes on the planet Earth. Plate tectonics may be only a slow moving, low energy secondary effect defined and set in motion by megacosmic accretion events. Permo-Carboniferous sediments of note are preserved or accumulated in relatively small rectangular to arcuate rift valleys and synclinal down warps, such as the Narraganset basin of Massachusetts, USA, and Paganzo basin in Argentina, S.A. These deposits and depocenters may originate from dynamic reinforcement/cancellation impact effects, as can be seen in the Basin Range of Nevada and Utah, USA. Large circular to oval sedimentary basins commonly include internal ring structures indicating post depositional subsidence and rebound adjustments with growth faulting, notable in the Illinois basin USA and Ordos basin in China. Recent impact events on the planet Jupiter, July 1994, lend increasing support towards an impact orogenic geologic paradigm on the planet Earth.

Impact basins in Southern Daedalia, Mars: Evidence for clustered impactors?

NASA Technical Reports Server (NTRS)

Frey, Herbert; Roark, James H.

1994-01-01

The distribution of ancient massifs and old cratered terrain in the southern Daedalia region indicate the presence of at least two and probably three impact basins of large size. One of these is located near where Craddock et al. placed their center for the Daedalia Basin, but it has very different ring diameters. These basins have rings exceeding 1000 km diameter and overlap significantly with centers separated by 500 to 600 km at nearly identical latitudes of -26 to -29 deg. The smaller westernmost basin appears slightly better preserved, but there is little evidence for obvious superposition that might imply a temporal sequence. Recognizing the improbability of random impacts producing aligned, nearly contemporaneous features, we suggest these basins may have resulted from clustered impactors.

Lunar impact basins: Stratigraphy, sequence and ages from superposed impact crater populations measured from Lunar Orbiter Laser Altimeter (LOLA) data

NASA Astrophysics Data System (ADS)

Fassett, C. I.; Head, J. W.; Kadish, S. J.; Mazarico, E.; Neumann, G. A.; Smith, D. E.; Zuber, M. T.

2012-02-01

Impact basin formation is a fundamental process in the evolution of the Moon and records the history of impactors in the early solar system. In order to assess the stratigraphy, sequence, and ages of impact basins and the impactor population as a function of time, we have used topography from the Lunar Orbiter Laser Altimeter (LOLA) on the Lunar Reconnaissance Orbiter (LRO) to measure the superposed impact crater size-frequency distributions for 30 lunar basins (D ≥ 300 km). These data generally support the widely used Wilhelms sequence of lunar basins, although we find significantly higher densities of superposed craters on many lunar basins than derived by Wilhelms (50% higher densities). Our data also provide new insight into the timing of the transition between distinct crater populations characteristic of ancient and young lunar terrains. The transition from a lunar impact flux dominated by Population 1 to Population 2 occurred before the mid-Nectarian. This is before the end of the period of rapid cratering, and potentially before the end of the hypothesized Late Heavy Bombardment. LOLA-derived crater densities also suggest that many Pre-Nectarian basins, such as South Pole-Aitken, have been cratered to saturation equilibrium. Finally, both crater counts and stratigraphic observations based on LOLA data are applicable to specific basin stratigraphic problems of interest; for example, using these data, we suggest that Serenitatis is older than Nectaris, and Humboldtianum is younger than Crisium. Sample return missions to specific basins can anchor these measurements to a Pre-Imbrian absolute chronology.

Lunar Impact Basins: Stratigraphy, Sequence and Ages from Superposed Impact Crater Populations Measured from Lunar Orbiter Laser Altimeter (LOLA) Data

NASA Technical Reports Server (NTRS)

Fassett, C. I.; Head, J. W.; Kadish, S. J.; Mazarico, E.; Neumann, G. A.; Smith, D. E.; Zuber, M. T.

2012-01-01

Impact basin formation is a fundamental process in the evolution of the Moon and records the history of impactors in the early solar system. In order to assess the stratigraphy, sequence, and ages of impact basins and the impactor population as a function of time, we have used topography from the Lunar Orbiter Laser Altimeter (LOLA) on the Lunar Reconnaissance Orbiter (LRO) to measure the superposed impact crater size-frequency distributions for 30 lunar basins (D = 300 km). These data generally support the widely used Wilhelms sequence of lunar basins, although we find significantly higher densities of superposed craters on many lunar basins than derived by Wilhelms (50% higher densities). Our data also provide new insight into the timing of the transition between distinct crater populations characteristic of ancient and young lunar terrains. The transition from a lunar impact flux dominated by Population 1 to Population 2 occurred before the mid-Nectarian. This is before the end of the period of rapid cratering, and potentially before the end of the hypothesized Late Heavy Bombardment. LOLA-derived crater densities also suggest that many Pre-Nectarian basins, such as South Pole-Aitken, have been cratered to saturation equilibrium. Finally, both crater counts and stratigraphic observations based on LOLA data are applicable to specific basin stratigraphic problems of interest; for example, using these data, we suggest that Serenitatis is older than Nectaris, and Humboldtianum is younger than Crisium. Sample return missions to specific basins can anchor these measurements to a Pre-Imbrian absolute chronology.

A Sneak Peek into Saheki Secret Layers

NASA Image and Video Library

2017-04-04

This image from NASA's Mars Reconnaissance Orbiter is of Saheki Crater, about 84 kilometers across, and located in the Southern highlands of Mars, to the north of Hellas Planitia. It's filled with beautiful alluvial fans that formed when water (likely melting snow) carried fine material, such as sand, silt and mud, from the interior crater rim down to the bottom of the crater. Two smaller craters impacted into the alluvial fan surface in Saheki, excavating holes that allow us to see what the fans look like beneath the surface. Exposed along the crater's interior walls, we can see that the fan is made up of multiple individual layers (white and purple tones in the enhanced color image) that were deposited on the floor (the green and brown tones). The brown, circular shapes on the fan layers are small impact craters. The map is projected here at a scale of 25 centimeters (9.8 inches) per pixel. [The original image scale is 26.2 centimeters (10.3 inches) per pixel (with 1 x 1 binning); objects on the order of 78 centimeters (30.7 inches) across are resolved.] North is up. https://photojournal.jpl.nasa.gov/catalog/PIA21577

Large Impact Basins on Mercury: Global Distribution, Characteristics, and Modification History from MESSENGER Orbital Data

NASA Technical Reports Server (NTRS)

Fassett, Caleb I.; Head, James W.; Baker, David M. H.; Zuber, Maria T.; Neumann, Gregory A.; Solomon, Sean C.; Klimczak, Christian; Strom, Robert G.; Chapman, Clark R.; Prockter, Louise M.;

Four Views of Mars in Northern Summer

NASA Technical Reports Server (NTRS)

1997-01-01

Four faces of Mars as seen on March 30, 1997 are presented in this montage of NASA Hubble Space Telescope images. Proceeding in the order upper-left, upper-right, lower-left, lower-right, Mars has rotated about ninety degrees between each successive time step. For example the Tharsis volcanoes, which are seen (between 7:30 and 9 o'clock positions) in mid-morning in the UPPER-RIGHT view, are seen near the late afternoon edge of the planet (about 3 o'clock position) in the lower-left image. All of these color images are composed of individual red (673 nanometers), green (502 nm), and blue (410 nm) Planetary Camera exposures.

Upper left: This view is centered on Ares Valles, where Pathfinder will land on July 4, 1997; the Valles Marineris canyon system stretches to the west across the lower left portion of the planet, while the bright, orangish desert of Arabia Planitia is to the east. The bright polar water-ice cap, surrounded by a dark ring of sand dunes, is obvious in the north; since it is northern summer and the pole is tilted toward us, the residual north polar cap is seen in its entirety in all four images. Acidalia Planitia, the prominent dark area fanning southward from the polar region, is thought to have a surface covered with dark sand. Numerous 'dark wind streaks' are visible to the south of Acidalia, resulting from wind-blown sand streaming out of the interiors of craters.

Upper right: The Tharsis volcanos and associated clouds are prominent in the western half of this view. Olympus Mons, spanning 340 miles (550 km) across its base and reaching an elevation of 16 miles (25 km), extends through the cloud deck near the western limb, while (from the south) Arsia Mons, Pavonis Mons, and Ascraeus Mons are to the west of center. Valles Marineris stretches to the east, and the Pathfinder landing site is shrouded in clouds near the afternoon limb.

Lower left: This relatively featureless sector of Mars stretches from the Elysium volcanic region in the west to the Tharsis volcanoes (shrouded by the bright clouds near the afternoon limb) in the east. The group of three dark specks just left of center are all that remain of Cerberus, a very prominent dark region during the Viking and Mariner 9 missions. This is an example of the remarkable large scale changes which can occur on Mars due to windblown dust: the former dark area has now been covered by a layer of bright dust, masking the underlying material.

Lower right: The dark Syrtis Major region dominates this image. Syrtis Major is one of the most prominent dark features on Mars, and has been visible since ground-based observers first peered at Mars through telescopes. The bright cloud at 3 o'clock is associated with Elysium Mons. The bright bluish-white feature near the southern limb of the planet is Hellas, a 1,200 mile (2,000 km) diameter impact basin formed by the collision of a large body with Mars long ago. Hellas is covered with dry ice frost and clouds during this season (winter in the south).

This image and other images and data received from the Hubble Space Telescope are posted on the World Wide Web on the Space Telescope Science Institute home page at URL http://oposite.stsci.edu/pubinfo/

Apollo 16 site geology and impact melts - Implications for the geologic history of the lunar highlands

DOE Office of Scientific and Technical Information (OSTI.GOV)

Spudis, P.D.

1984-11-15

The geology of the Apollo 16 site is reconsidered on the basis of data from photogeology, geochemical remote sensing, and lunar samples. The site possesses an upper surface of anorthositic gabbro and related rocks. Mafic components were deposited as basin ejecta. The events involved in its geological evolution were the Nectaris impact and the Imbrium impact. The role of large, local craters in the history of the region was to serve as topographic depressions to accumulate basin ejecta. The most abundant melt composition at Apollo 16 is an aluminous variety of LKFM basalt supplied by the Nectaris impact as ejectedmore » basin impact melt. The mafic LKFM melt may have been supplied by the Imbrium impact. More aluminous melt groups are probably derived from local, small craters. The remainder of the deposits in the region are composed of anorthositic clastic debris derived from the Nectaris basin, the local crustal substrate, and Imbrium and other basins.« less

Chicxulub impact basin: Gravity characteristics and implications for basin morphology and deep structure

NASA Technical Reports Server (NTRS)

Sharpton, Virgil L.; Burke, Kevin; Hall, Stuart A.; Lee, Scott; Marin, Luis E.; Suarez, Gerardo; Quezada-Muneton, Juan Manuel; Urrutia-Fucugauchi, Jaime

1993-01-01

The K-T-aged Chicxulub Impact Structure is buried beneath the Tertiary carbonate rocks of the Northern Yucatan Platform. Consequently its morphology and structure are poorly understood. Reprocessed Bouguer (onshore) and Free Air (offshore) gravity data over Northern Yucatan reveal that Chicxulub may be a 200-km-diameter multi-ring impact basin with at least three concentric basin rings. The positions of these rings follow the square root of 2 spacing rule derived empirically from analysis of multi-ring basins on other planets indicating that these rings probably correspond to now-buried topographic basin rings. A forward model of the gravity data along a radial transect from the southwest margin of the structure indicates that the Chicxulub gravity signature is compatible with this interpretation. We estimate the basin rim diameter to be 204 +/- 16 km and the central peak ring diameter (D) is 104 +/- 6 km.

Stratigraphy of the Caloris Basin, Mercury: Implications for Volcanic History and Basin Impact Melt

NASA Technical Reports Server (NTRS)

Ernst, Carolyn M.; Denevi, Brett W.; Barnouin, Olivier S.; Klimczak, Christian; Chabot, Nancy L.; Head, James W.; Murchie, Scott L.; Neumann, Gregory A.; Prockter, Louis M.; Robinson, Mark S.;

Combined top-down and bottom-up climate change impact assessment for the hydrological system in the Vu Gia- Thu Bon River Basin.

PubMed

Tra, Tran Van; Thinh, Nguyen Xuan; Greiving, Stefan

2018-07-15

Vu Gia- Thu Bon (VGTB) River Basin, located in the Central Coastal zone of Viet Nam currently faces water shortage. Climate change is expected to exacerbate the challenge. Therefore, there is a need to study the impacts of climate change on water shortage in the river basin. The study adopts a combined top-down and bottom-up climate change impact assessment to address the impacts of climate change on water shortage in the VGTB River Basin. A MIKE BASIN water balance model for the river basin was established to simulate the response of the hydrological system. Simulations were performed through parametrically varying temperature and precipitation to determine the vulnerability space of water shortage. General Circulation Models (GCMs) were then utilized to provide climate projections for the river basin. The output from GCMs was then mapped onto the vulnerability space determined earlier. In total, 9 out of 55 water demand nodes in the simulation are expected to face problematic conditions as future climate changes. Copyright © 2018 Elsevier B.V. All rights reserved.

Towards Understanding the Impact of Production Techniques and Regulations on Widely Varying Methane Emission Rates in Western Basins

NASA Astrophysics Data System (ADS)

Robertson, A.; Edie, R.; Soltis, J.; Field, R. A.; Murphy, S. M.

2017-12-01

Recent airborne and mobile lab-based studies by our group and others have demonstrated that production-normalized emission rates of methane can vary dramatically between different Western basins. Three oil and gas basins that are geographically near one another and have relatively similar production characteristics (all three basins produce a mix of natural gas and condensate) have starkly different production-normalized methane emission rates at both the facility and basin-wide levels. This presentation will review previously published data on methane emissions from these basins (Denver Julesburg, Uintah, and Upper Green River) and present new measurement work supporting and expanding upon previous estimates. Beyond this, we use facility level data emissions data combined with information about the date of last upgrade to determine what impact regulations have had on methane emission rates from facilities within the basins. We also investigate what impact different approaches to production may have, in particular the role of having many individual wells processed at a central facility with high throughput is analyzed in terms of its impact on methane emissions.

Towards Understanding the Impact of Production Techniques and Regulations on Widely Varying Methane Emission Rates in Western Basins

NASA Astrophysics Data System (ADS)

Regayre, L. A.; Johnson, J. S.; Yoshioka, M.; Pringle, K.; Sexton, D.; Booth, B.; Mann, G.; Lee, L.; Bellouin, N.; Lister, G. M. S.; Johnson, C.; Johnson, B. T.; Mollard, J.; Carslaw, K. S.

2016-12-01

Recent airborne and mobile lab-based studies by our group and others have demonstrated that production-normalized emission rates of methane can vary dramatically between different Western basins. Three oil and gas basins that are geographically near one another and have relatively similar production characteristics (all three basins produce a mix of natural gas and condensate) have starkly different production-normalized methane emission rates at both the facility and basin-wide levels. This presentation will review previously published data on methane emissions from these basins (Denver Julesburg, Uintah, and Upper Green River) and present new measurement work supporting and expanding upon previous estimates. Beyond this, we use facility level data emissions data combined with information about the date of last upgrade to determine what impact regulations have had on methane emission rates from facilities within the basins. We also investigate what impact different approaches to production may have, in particular the role of having many individual wells processed at a central facility with high throughput is analyzed in terms of its impact on methane emissions.

Chemical speciation and bioaccessibility of lead in surface soil and house dust, Lavrion urban area, Attiki, Hellas.

PubMed

Demetriades, Alecos; Li, Xiangdong; Ramsey, Michael H; Thornton, Iain

2010-12-01

In the Lavrion urban area study, Hellas, a five-step sequential extraction method was applied on samples of 'soil' (n = 224), affected by long-term mining and metallurgical activities, and house dust (n = 127), for the purpose of studying the potential bioaccessibility of lead and other metals to humans. In this paper, the Pb concentrations in soil and house dust samples are discussed, together with those in rocks and children's blood. Lead is mainly associated with the carbonate, Fe-Mn oxides and residual fractions in soil and house dust. Considering the very low pH of gastric fluids (1-3), a high amount of metals, present in soil (810-152,000 mg/kg Pb) and house dust (418-18,600 mg/kg Pb), could be potentially bioaccessible. Consequently, children in the neighbourhoods with a large amount of metallurgical processing wastes have high blood-Pb concentrations (5.98-60.49 μg/100 ml; median 17.83 μg/100 ml; n = 235). It is concluded that the Lavrion urban and sub-urban environment is extremely hazardous to human health, and the Hellenic State authorities should urgently tackle this health-related hazard in order to improve the living conditions of local residents.

Sampling South Pole-Aitken Basin: The Moonrise Approach

NASA Technical Reports Server (NTRS)

Jolliff, B. L.; Shearer, C. K.; Cohen, B. A.

2012-01-01

The South Pole-Aitken basin (SPA) is the largest of the giant impact basins in the inner Solar System, and its location on Earth s Moon makes it the most accessible. Exploration of SPA through direct collection and analysis of representative materials addresses issues as fundamental as the characteristics of the chemical reservoir from which the Moon originated, early differentiation and production of crust and development of global asymmetry, relationships between magmatic activity and internal thermal evolution, and effects of giant impact events on the terrestrial planets. Owing to its great size and superposition relationships with other lunar impact basins, SPA is the oldest and as such anchors the lunar chronology. Moreover, numerous large impact craters and basins are contained within it such that materials (rocks) of the SPA basin contain a record of the early impact chronology, one less likely to have been affected by the large, late nearside basins (e.g., Imbrium). Understanding the early basin chronology is key to deciphering the sequence and effects of early giant impact bombardment of the inner Solar System. That record exists on the Moon, and materials of the SPA basin will allow us to read that record. Knowledge of the early bombardment history will test - and may reshape - a key paradigm relating to early Solar System evolution. Did the planets form with the alignment of today, or was there a major reorientation of the giant planets that led to destabilization of asteroid orbits, and a cataclysmic bombardment of the inner Solar System hundreds of millions of years after accretion of the planets? Implications include understanding environments for early life-supporting habitats on Earth and Mars, and relationships to new observations of extra-solar planetary systems.

Comparative water quality of lightly-and moderately-impacted streams in the southern Blue Ridge Mountains, USA

Treesearch

Katie Price; David S. Leigh

2006-01-01

For less-developed regions like the Blue Ridge Mountains. data are limited that link basin-scale land use with stream quality. Two pairs of lightly-impacted (90-100% forested) and moderately-impacted (7&80% forested) sub-basins of the upper Little Tennessee River basin in the southern Blue Ridge were identified for comparison. The pairs contain physically similar...

Characterizing the impact of spatiotemporal variations in stormwater infrastructure on hydrologic conditions

NASA Astrophysics Data System (ADS)

Jovanovic, T.; Mejia, A.; Hale, R. L.; Gironas, J. A.

2015-12-01

Urban stormwater infrastructure design has evolved in time, reflecting changes in stormwater policy and regulations, and in engineering design. This evolution makes urban basins heterogeneous socio-ecological-technological systems. We hypothesize that this heterogeneity creates unique impact trajectories in time and impact hotspots in space within and across cities. To explore this, we develop and implement a network hydro-engineering modeling framework based on high-resolution digital elevation and stormwater infrastructure data. The framework also accounts for climatic, soils, land use, and vegetation conditions in an urban basin, thus making it useful to study the impacts of stormwater infrastructure across cities. Here, to evaluate the framework, we apply it to urban basins in the metropolitan areas of Phoenix, Arizona. We use it to estimate different metrics to characterize the storm-event hydrologic response. We estimate both traditional metrics (e.g., peak flow, time to peak, and runoff volume) as well as new metrics (e.g., basin-scale dispersion mechanisms). We also use the dispersion mechanisms to assess the scaling characteristics of urban basins. Ultimately, we find that the proposed framework can be used to understand and characterize the impacts associated with stormwater infrastructure on hydrologic conditions within a basin. Additionally, we find that the scaling approach helps in synthesizing information but it requires further validation using additional urban basins.

The HELLAS2XMM survey. IV. Optical identifications and the evolution of the accretion luminosity in the Universe

NASA Astrophysics Data System (ADS)

Fiore, F.; Brusa, M.; Cocchia, F.; Baldi, A.; Carangelo, N.; Ciliegi, P.; Comastri, A.; La Franca, F.; Maiolino, R.; Matt, G.; Molendi, S.; Mignoli, M.; Perola, G. C.; Severgnini, P.; Vignali, C.

2003-10-01

We present results from the photometric and spectroscopic identification of 122 X-ray sources recently discovered by XMM-Newton in the 2-10 keV band (the HELLAS2XMM 1dF sample). Their flux cover the range 8*E-15-4*E-13 erg cm-2 s-1 and the total area surveyed is 0.9 square degrees. One of the most interesting results (which is found also in deeper sourveys) is that about 20% of the hard X-ray selected sources have an X-ray to optical flux ratio (X/O) ten times or more higher than that of optically selected AGN. Unlike the faint sources found in the ultra-deep Chandra and XMM-Newton surveys, which reach X-ray (and optical) fluxes more than one order of magnitude lower than the HELLAS2XMM survey sources, many of the extreme X/O sources in our sample have Rprotect la25 and are therefore accessible to optical spectroscopy. We report the identification of 13 sources with X/Oprotect ga10 (to be compared with 9 sources known from the deeper, pencil-beam surveys). Eight of them are narrow line QSO (seemingly the extension to very high luminosity of the type 2 Seyfert galaxies), four are broad line QSO. The results from our survey are also used to make reliable predictions about the luminosity of the sources not yet spectroscopically identified, both in our sample and in deeper Chandra and XMM-Newton samples. We then use a combined sample of 317 hard X-ray selected sources (HELLAS2XMM 1dF, Chandra Deep Field North 1Msec, Chandra SSA13 and XMM-Newton Lockman Hole flux limited samples), 221 with measured redshifts, to evaluate the cosmological evolution of the hard X-ray source's number and luminosity densities. Looking backward in time, the low luminosity sources (log L2-10 keV=43-44 erg s-1) increase in number at a much slower rate than the very high luminosity sources (log L2-10 keV >44.5 erg s-1), reaching a maximum around z=1 and then levelling off beyond z=2. This translates into an accretion driven luminosity density which is dominated by sources with log L2-10 keV <44.5 erg s-1 up to at least z=1, while the contribution of the same sources and of those with log L2-10 keV >44.5 erg s-1 appear, with yet rather large uncertainties, to be comparable between z=2 and 4. Based on observations collected at the European Southern Observatory, La Silla and Paranal, Chile, and at the Telescopio Nazionale Galileo, Roque de Los Muchachos, La Palma, TF, Spain. Based also on observations made with XMM-Newton, an ESA science mission. Table 1 is only available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/409/79

The Sculptured Hills of the Taurus Highlands: Implications for the relative age of Serenitatis, basin chronologies and the cratering history of the Moon

USGS Publications Warehouse

Spudis, P.D.; Wilhelms, D.E.; Robinson, M.S.

2011-01-01

New images from the Lunar Reconnaissance Orbiter Camera show the distribution and geological relations of the Sculptured Hills, a geological unit widespread in the highlands between the Serenitatis and Crisium basins. The Sculptured Hills shows knobby, undulating, radially textured, and plains-like morphologies and in many places is indistinguishable from the similarly knobby Alpes Formation, a facies of ejecta from the Imbrium basin. The new LROC image data show that the Sculptured Hills in the Taurus highlands is Imbrium ejecta and not directly related to the formation of the Serenitatis basin. This occurrence and the geological relations of this unit suggests that the Apollo 17 impact melts may not be not samples of the Serenitatis basin-forming impact, leaving their provenance undetermined and origin unexplained. If the Apollo 17 melt rocks are Serenitatis impact melt, up to half of the basin and large crater population of the Moon was created within a 30 Ma interval around 3.8 Ga in a global impact "cataclysm." Either interpretation significantly changes our view of the impact process and history of the Earth-Moon system. Copyright 2011 by the American Geophysical Union.

Constraints on the formation and properties of a Martian lobate debris apron: Insights from high-resolution topography, SHARAD radar data, and a numerical ice flow model

NASA Astrophysics Data System (ADS)

Parsons, Reid; Holt, John

2016-03-01

Lobate debris aprons (LDAs) are midlatitude deposits of debris-covered ice formed during one or more periods of glaciation during the Amazonian period. However, little is known about the climate conditions that led to LDA formation. We explore a hypothesis in which a single, extended period of precipitation of ice on the steep slopes of Euripus Mons (45°S, 105°E—east of the Hellas Basin) produced a flowing ice deposit which was protected from subsequent ablation to produce the LDA found at this location. We test this hypothesis with a numerical ice flow model using an ice rheology based on low-temperature ice deformation experiments. The model simulates ice accumulation and flow for the northern and southern lobes of the Euripus Mons LDA using basal topography constrained by data from the Shallow Radar (SHARAD) and a range of ice viscosities (determined by ice temperature and ice grain size). Simulations for the northern lobe of the Euripus LDA produce good fits to the surface topography. Assuming an LDA age of ˜60 Myr and an expected temperature range of 200 to 204 K (for various obliquities) gives an ice grain size of ≈2 mm. Simulations of the southern section produce poor fits to surface topography and result in much faster flow timescales unless multiple ice deposition events or higher ice viscosities are considered.

Scientists Track 'Perfect Storm' on Mars

NASA Technical Reports Server (NTRS)

2001-01-01

Two dramatically different faces of our Red Planet neighbor appear in these comparison images showing how a global dust storm engulfed Mars with the onset of Martian spring in the Southern Hemisphere. When NASA's Hubble Space Telescope imaged Mars in June, the seeds of the storm were caught brewing in the giant Hellas Basin (oval at 4 o'clock position on disk) and in another storm at the northern polar cap.

When Hubble photographed Mars in early September, the storm had already been raging across the planet for nearly two months obscuring all surface features. The fine airborne dust blocks a significant amount of sunlight from reaching the Martian surface. Because the airborne dust is absorbing this sunlight, it heats the upper atmosphere. Seasonal global Mars dust storms have been observed from telescopes for over a century, but this is the biggest storm ever seen in the past several decades.

Mars looks gibbous in the right photograph because it is 26 million miles farther from Earth than in the left photo (though the pictures have been scaled to the same angular size), and our viewing angle has changed. The left picture was taken when Mars was near its closest approach to Earth for 2001 (an event called opposition); at that point the disk of Mars was fully illuminated as seen from Earth because Mars was exactly opposite the Sun.

Both images are in natural color, taken with Hubble's Wide Field Planetary Camera 2.

The Seasonal Cycle of Water Vapour on Mars from Assimilation of Thermal Emission Spectrometer Data

NASA Technical Reports Server (NTRS)

Steele, Liam J.; Lewis, Stephen R.; Patel, Manish R.; Montmessin, Franck; Forget, Francois; Smith, Michael D.

2014-01-01

We present for the first time an assimilation of Thermal Emission Spectrometer (TES) water vapour column data into a Mars global climate model (MGCM). We discuss the seasonal cycle of water vapour, the processes responsible for the observed water vapour distribution, and the cross-hemispheric water transport. The assimilation scheme is shown to be robust in producing consistent reanalyses, and the global water vapour column error is reduced to around 2-4 pr micron depending on season. Wave activity is shown to play an important role in the water vapour distribution, with topographically steered flows around the Hellas and Argyre basins acting to increase transport in these regions in all seasons. At high northern latitudes, zonal wavenumber 1 and 2 stationary waves during northern summer are responsible for spreading the sublimed water vapour away from the pole. Transport by the zonal wavenumber 2 waves occurs primarily to the west of Tharsis and Arabia Terra and, combined with the effects of western boundary currents, this leads to peak water vapour column abundances here as observed by numerous spacecraft. A net transport of water to the northern hemisphere over the course of one Mars year is calculated, primarily because of the large northwards flux of water vapour which occurs during the local dust storm around L(sub S) = 240-260deg. Finally, outlying frost deposits that surround the north polar cap are shown to be important in creating the peak water vapour column abundances observed during northern summer.

Inventory of Multiring Basins on the Moon After the Clementine Mission

NASA Astrophysics Data System (ADS)

Spudis, P. D.

1995-09-01

Multi-ring basins (impact craters greater than 300 km in diameter, regardless of presently expressed morphology; [1, 2]) are of primary importance in the excavation and redistribution of crustal materials and serve as the loci for the accumulation of extruded lavas on the Moon. Understanding their distribution and configuration is important in order to reconstruct the basin-forming impact [2]. The Clementine mission has made the first global maps of the Moon, including altimetry from a laser ranging experiment [3, 4]. This map permits the characterization of long-wavelength topographic features of the lunar crust, including the most prominent and important features, multi-ring basins. We have now surveyed the entire Moon with laser altimetry data from Clementine and have inventoried the global basin population. Many of the most obscure and degraded basins are strikingly expressed in the topographic data. Basins such as Mendel-Rydberg, a nearly obliterated ancient basin (600 km diameter, 5 km deep) south of Orientale, displays nearly as much relief as the "pristine" Orientale basin (900 km diameter; 7 km depth) [5]. The Fecunditatis basin, an obscure quasi-circular feature south of Mare Crisium [3], displays considerable topographic prominence, including an average relief of about 5 km. However, not all of the ancient basins are so deep: the Mutus-Vlacq basin [3], south of Nectaris, is clearly visible in the altimetry [5], but is only 1 to 1.5 km deep. Other basins that appear very ill-defined in the altimetry, yet clearly are present as regional depressions include the Australe, Tranquillitatis, and Margims basins [3]. That both relatively deep and shallow basins exist on the Moon is not surprising; what is remarkable is that there is no correlation between basin depth and geologic age. Apparently, basin morphology is more dependent on local conditions (e.g., crustal thickness, lithospheric conditions at the time of impact) than age. Another unusual expression of topography for a basin is that of the degraded Lomonosov-Fleming basin [3,6]. This feature appears as a quasi-circular, smooth plateau of nearly constant elevation about 500 km across. Such an expression is likely caused by infilling of the basin with ancient mare basalts, covered by highland plains and reexposed as the ejecta of dark halo impact craters [7,8]. This interpretation is supported by the mafic signature of the plains in this region in the Clementine global color image [9] and the presense of elevated amounts of iron in the highland crust here [10]. The altimetry data also show many depressions that are likely to be previously unrecognized basins. For example, depressions near the crater Darwin (20 degrees S, 70 degrees W; basin about 300 km diameter), eastern Mare Frigoris (55 degrees N, 30 degrees W; basin about 700 km across), and east of Mare Humboldtianum (60 degrees N, 130 degrees E; basin about 400 km diameter) are probably degraded impact basins. To date, over 45 basins and their rings have been mapped on the Moon and the relief and volumes of the basins have been measured. Work continues on the analysis of this numerical data, which should give insight into the processes of basin formation and planetary evolution. References: [1] Wilhelms D. E. (1987) USGS Prof. Pap. 1348, 302 pp. [2] Spudis P. D. (1993) Geology of Multi-Ring Impact Basins, Cambridge Univ., 263 pp. [3] Nozette S. et al. (1994) Science, 266, 1835. [4] Zuber M. T. et al. (1994) Science, 266, 1839. [5] Spudis P. D. et al. (1994) Science, 266, 1848. [6] Wilhelms D. and El-Baz F. (1977) USGS Map I-948. [7] Schultz P. H. and Spudis P. D. (1979) Proc. LPSC 10th, 2899. [8] Schultz P. H. and Spudis P. D. (1982) Nature, 302, 233. [9] Lucey P. G. et al. (1994) Science, 266, 1855. [10] Lucey P. G. et al. (1995) Science, 268, 1150.

The Apollo peak-ring impact basin: Insights into the structure and evolution of the South Pole-Aitken basin

NASA Astrophysics Data System (ADS)

Potter, Ross W. K.; Head, James W.; Guo, Dijun; Liu, Jianzhong; Xiao, Long

2018-05-01

The 492 km-diameter Apollo impact basin post-dates, and is located at the inner edge of, the ∼2240 km-diameter South Pole-Aitken (SPA) basin, providing an opportunity to assess the SPA substructure and lateral heterogeneity. Gravity Recovery and Interior Laboratory gravity data suggest an average crustal thickness on the floor of SPA of ∼20 km and within the Apollo basin of ∼5 km, yet remote sensing data reveal no conclusive evidence for the presence of exposed mantle material. We use the iSALE shock physics code to model the formation of the Apollo basin and find that the observational data are best fit by the impact of a 40 km diameter body traveling at 15 km/s into 20-40 km thick crustal material. These results strongly suggest that the Apollo impact occurred on ejecta deposits and collapsed crustal material of the SPA basin and could help place constraints on the location, size and geometry of the SPA transient cavity. The peak ring in the interior of Apollo basin is plausibly interpreted to be composed of inwardly collapsed lower crustal material that experienced peak shock pressures in excess of 35 GPa, consistent with remote sensing observations that suggest shocked plagioclase. Proposed robotic and/or human missions to SPA and Apollo would present an excellent opportunity to test the predictions of this work and address many scientific questions about SPA basin evolution and structure.

Is There any Relationship Between the Santa Elena Depression and Chicxulub Impact Crater, Northwestern Yucatan Peninsula, Mexico?

NASA Astrophysics Data System (ADS)

Lefticariu, L.

2005-05-01

The Terminal Cretaceous Chicxulub Impact Crater had a strong control on the depositional and diagenetic history of the northern Yucatan Platform during most of the Cenozoic Era. The Chicxulub Sedimentary Basin (henceforth Basin), which approximately coincides with the impact crater, is circumscribed by a concentration of karstic sinkholes known as the Ring of Cenotes. Santa Elena Depression (henceforth Depression) is the name proposed for the bowl-shaped buried feature, first contoured by geophysical studies, immediately south of the Basin, in the area where the Ticul 1 and UNAM 5 wells were drilled. Lithologic, petrographic, and biostratigraphic data on PEMEX, UNAM, and ICDP cores show that: 1) Cenozoic deposits are much thicker inside the Basin than inside the Depression, 2) in general, the Cenozoic formations from inside the Depression are the thickest among those outside the Basin, 3) variably dolomitized pelagic or outer-platform wackestone or mudstone occur both inside the Basin and Depression, 4) the age of the deeper-water sedimentary carbonate rocks is Paleocene-Eocene inside the Basin and Paleocene?-Early Eocene inside the Depression, 5) the oldest formations that crop out are of Middle Eocene age at the edge of the Basin and Early-Middle Eocene age inside the Depression, 6) saline lake deposits, that consist chiefly of anhydrite, gypsum, and fine carbonate, and also contain quartz, chert, clay, zeolite, potassium feldspar, pyrite, and fragments of wood, are present in the Cenozoic section of the UNAM 5 core between 282 and 198 m below the present land surface, 7) the dolomite, subaerial exposure features (subaerial crusts, vugs, karst, dedolomite), and vug-filling cement from the Eocene formations are more abundant inside the Depression than inside the Basin. The depositional environments that are proposed for explaining the Cenozoic facies succession within the Santa Elena Depression are: 1) deeper marine water (Paleocene?-Early Eocene), 2) relatively isolated saline lake (Middle Eocene), and 3) shallow marine water (Middle-Late Eocene?). In places, the deeper-water facies are similar to those within the Chicxulub Sedimentary Basin. The shallow-water facies is similar to those occurring outside the Basin. In general, quartz and silicates are rare in the Cenozoic sedimentary carbonate of the northwestern Yucatan Peninsula. Therefore, their presence in the UNAM 5 core could be attributed to either impact breccia reworking or silicic volcanic processes. Quartz, chert, zeolite, and clay also are common in the suevite breccia of both Yax-1 and UNAM 5 cores. The fact that the Santa Elena Depression was a distinct sedimentary basin during much of the Paleogene could be explained by any or a combination of the following hypotheses: 1) In spite of being located outside the cenote ring, the Depression is a sub-basin of the larger and deeper Chicxulub Sedimentary Basin and is therefore located within the Chicxulub Impact Crater, 2) the Depression coincides with an impact crater distinct from the Chicxulub Impact Crater, 3) the Depression formed after the Chicxulub bolide impact due to slumping, crater wall failure, or larger-scale tectonic processes. The lack of conclusive evidence for multiple impact breccia layers in the northwestern Yucatan Peninsula, corroborated with the presence on top of the impact breccia from UNAM 5 core of deeper-water limestone similar to that of Late Paleocene-Early Eocene age from Yax-1 core, would be more consistent with either the first or third hypothesis.

Comparative study of compensation mechanism of lunar impact basins from new gravity field model of SELENE (Kaguya)

NASA Astrophysics Data System (ADS)

Namiki, N.; Sugita, S.; Matsumoto, K.; Goossens, S.; Ishihara, Y.; Noda, H.; Ssasaki, S.; Iwata, T.; Hanada, H.; Araki, H.

2009-04-01

The gravity field is a fundamental physical quantity for the study of the internal structure and the evolution of planetary bodies. The most significant problem of the previous lunar gravity models, however, is the lack of direct observations of the far side gravity signals [1]. We then developed a satellite-to-satellite Doppler tracking sub-system for SELENE [2]. In this study, we adopt our new gravity field model with nearly full coverage of the lunar far side to discuss dichotomy of the lunar basins. Because all the nearside impact basins are filled with extensive mare basalt deposits, it is difficult to estimate the subsurface structures, such as uplift of the Moho surface, from gravity measurements. In contrast, far-side impact basins have much less or no mare basalt coverage. This may allow us to investigate the internal structure underneath impact basins. Such knowledge will be important in understanding the response of a solid planetary body to large meteoritic impacts and also the thermal state of the Moon during the late heavy bombardment period. There are distinctive differences between the anomalies of the near side principal mascons and the far side basins. As shown previously [1, 3], the near side principal mascons have sharp shoulders with a gravity plateau and a weakly negative gravity anomaly in the surroundings. In contrast, the far side basins are characterized by concentric rings of positive and negative anomalies. The circular gravity highs agree well with the topographic rims of the basins revealed by SELENE topography model STM-359_grid-02 [4]. In our gravity model, Orientale, Mendel-Rydberg, Lorentz, and Humboldtianum show more affinity with the far side basins than the near side principal mascons [5]. Korolev, Mendeleev, Planck, and Lorentz basins have sharp central peaks of which magnitude in free-air anomalies is almost equivalent to the one in Bouguer anomalies. On the other hand, Orientale, Mendel-Rydberg, Humboldtianum, Moscoviense, and Freundlich-Sharonov basins have a broad peak of which magnitude in free-air anomalies is 20 to 60 % smaller than the one in Bouguer anomalies. We call the former basins Type I and the latter Type II. The central gravity high of Type I basins in Bouguer anomalies suggests the existence of excess mass below the center. Because mare fill is absent from Type I basins, the central gravity high is most likely a manifestation of mantle uplift beneath the basin. The peak height of positive Bouguer anomalies of Type II ranges from 400 to 900 mGal in comparison to those in free-air anomalies from 250 to 500 mGal. This difference can be attributed to local compensation at the center of the Type II basins. We propose a brittle deformation resulting from a load of uplifted mantle. Little relation between the class and formation age is found. On the other hand, there are fewer large lunar basins on the far side. It is unlikely that large impacts concentrated on one side of the Moon and smaller impacts on the other side, as crater diameter depends mostly on impacting energy and momentum, not the properties of the target [6]. A plausible hypothesis is that the primary mascon basins on the near side have deformed more after their initial formation. References: [1] A. S. Konopliv et al., Icarus, 150, 1 (2001). [2] T. Iwata et al., JGSJ, 47, 558 (2001). [3] F. G. Lemoine et al., JGR, 102, 16,339, (1997). [4] H. Araki et al., submitted to Science (2009). [5] N. Namiki et al., accepted by Science (2009). [6] H. J. Melosh, Impact Cratering: A Geologic Process (1989).

Crustal Thickness and Magnetization beneath Crisium and Moscoviense Lunar Impact Basins

NASA Astrophysics Data System (ADS)

Quesnel, Y.

2016-12-01

The recent NASA GRAIL mission allowed to derive a high-resolution model of the Moon's crustal thickness. It revealed that the Mare Crisium and Moscoviense large impact basins have the thinnest (< 7-8 km) crust of the Moon. On the other hand, significative magnetic field anomalies were measured over these basins by Lunar Prospector and Kaguya magnetometers. The Crisium lunar impact basin shows two localized intense ( 10 nT at 30 km of altitude) magnetic field anomalies located nearby its North and South borders, while Moscoviense shows a relatively-intense ( 4-5 nT at 30 km) central magnetic field anomaly. In details, these two anomalies are exactly located where the thinnest (<1-3 km) crust within the basins is predicted by the crustal thickness models. In this study we investigate this apparent anti-correlation by modeling the sources of these potential field data using several forward approaches in 2D and 3D. The parameters of the crustal source models are constrained by density and magnetization measurements on APOLLO samples, and by standard values for the lunar mantle and crust. Several possible models will be shown for the two basins. Preliminary results suggest that, beneath the thin Mare basalt layer seen at the floor of both basins, a magnetized layer with laterally-varying thickness is required. This layer may correspond to an impact melt sheet. We here exclude the hypothesis that a part of the lunar upper mantle could be magnetized beneath these basins (perhaps due to post-impact processes?), largely reducing the range of possible depths for the magnetic sources.

Variation in multiring basic structures as a function of impact angle

NASA Technical Reports Server (NTRS)

Wichman, R. W.; Schultz, P. H.

1992-01-01

Previous studies have demonstrated that the impact process in the laboratory varies as a function of impact angle. This variation is attributed to changes in energy partitioning and projectile failure during the impact and, in simple craters, produces a sequence of progressively smaller and more asymmetric crater forms as impact angle decreases from approximately 20 degrees. Variations in impact angle can produce differences in the appearance of multiring impact basins. Comparisons of Orientale to the more oblique impact structure at Crisium also suggests that these differences primarily reflect the degree of cavity collapse. The relative changes in massif ring topography, basin scarp relief, and the distribution of peripheral mare units are consistent with a reduction in degree of cavity collapse with decreasing impact angle. The prominent uprange basin scarps and the restriction of tectonically derived peripheral mare units along uprange ring structures also may indicate an uprange enhancement of failure during cavity collapse. Finally, although basin ring faults appear to be preferred pathways for mare volcanism, fault-controlled peripheral mare volcanism occurs most readily uprange of an oblique impact; elsewhere such volcanism apparently requires superposition of an impact structure on the ring fault.

The origin of lunar mascon basins.

PubMed

Melosh, H J; Freed, Andrew M; Johnson, Brandon C; Blair, David M; Andrews-Hanna, Jeffrey C; Neumann, Gregory A; Phillips, Roger J; Smith, David E; Solomon, Sean C; Wieczorek, Mark A; Zuber, Maria T

2013-06-28

High-resolution gravity data from the Gravity Recovery and Interior Laboratory spacecraft have clarified the origin of lunar mass concentrations (mascons). Free-air gravity anomalies over lunar impact basins display bull's-eye patterns consisting of a central positive (mascon) anomaly, a surrounding negative collar, and a positive outer annulus. We show that this pattern results from impact basin excavation and collapse followed by isostatic adjustment and cooling and contraction of a voluminous melt pool. We used a hydrocode to simulate the impact and a self-consistent finite-element model to simulate the subsequent viscoelastic relaxation and cooling. The primary parameters controlling the modeled gravity signatures of mascon basins are the impactor energy, the lunar thermal gradient at the time of impact, the crustal thickness, and the extent of volcanic fill.

Sociodemographic and socioeconomic determinants of health services utilization in Greece: the Hellas Health I study.

PubMed

Tountas, Yannis; Oikonomou, Nikolaos; Pallikarona, Georgia; Dimitrakaki, Christine; Tzavara, Chara; Souliotis, Kyriakos; Mariolis, Anargiros; Pappa, Evelina; Kontodimopoulos, Nick; Niakas, Dimitris

2011-02-01

The purpose of the study was to estimate the demographic and socioeconomic determinants of utilization of the Greek primary and hospital health care services. Data were obtained from the cross-sectional nationwide household survey Hellas Health I (2006). The sample (N = 1005) was representative of the Greek adult population in terms of age and residency, and was selected by means of a three-stage, proportional-to-size sampling design. The presence of a family doctor was reported in a higher degree by participants of higher social classes and private insurance. After adjusting for self-perceived general health and chronic illness, contacts with health care professionals during the past four weeks were found less for residents of rural areas, while contacts with health care professionals during the past 12 months were found less for men than women, for individuals without private insurance and for individuals of lower education. More out-of-pocket payments were reported by the 34-44 age group, rural area residents and individuals with private insurance. Higher use of private health care services was reported by participants of higher social classes and residents of rural areas and private insurance. Only hospital admissions were not directly influenced by demographic and socioeconomic factors. The findings imply the existence of inequities in access and use of primary health services with clear implications to related policies.

Lunar impact basins revealed by Gravity Recovery and Interior Laboratory measurements

PubMed Central

Neumann, Gregory A.; Zuber, Maria T.; Wieczorek, Mark A.; Head, James W.; Baker, David M. H.; Solomon, Sean C.; Smith, David E.; Lemoine, Frank G.; Mazarico, Erwan; Sabaka, Terence J.; Goossens, Sander J.; Melosh, H. Jay; Phillips, Roger J.; Asmar, Sami W.; Konopliv, Alexander S.; Williams, James G.; Sori, Michael M.; Soderblom, Jason M.; Miljković, Katarina; Andrews-Hanna, Jeffrey C.; Nimmo, Francis; Kiefer, Walter S.

2015-01-01

Observations from the Gravity Recovery and Interior Laboratory (GRAIL) mission indicate a marked change in the gravitational signature of lunar impact structures at the morphological transition, with increasing diameter, from complex craters to peak-ring basins. At crater diameters larger than ~200 km, a central positive Bouguer anomaly is seen within the innermost peak ring, and an annular negative Bouguer anomaly extends outward from this ring to the outer topographic rim crest. These observations demonstrate that basin-forming impacts remove crustal materials from within the peak ring and thicken the crust between the peak ring and the outer rim crest. A correlation between the diameter of the central Bouguer gravity high and the outer topographic ring diameter for well-preserved basins enables the identification and characterization of basins for which topographic signatures have been obscured by superposed cratering and volcanism. The GRAIL inventory of lunar basins improves upon earlier lists that differed in their totals by more than a factor of 2. The size-frequency distributions of basins on the nearside and farside hemispheres of the Moon differ substantially; the nearside hosts more basins larger than 350 km in diameter, whereas the farside has more smaller basins. Hemispherical differences in target properties, including temperature and porosity, are likely to have contributed to these different distributions. Better understanding of the factors that control basin size will help to constrain models of the original impactor population. PMID:26601317

Lunar impact basins revealed by Gravity Recovery and Interior Laboratory measurements.

PubMed

Neumann, Gregory A; Zuber, Maria T; Wieczorek, Mark A; Head, James W; Baker, David M H; Solomon, Sean C; Smith, David E; Lemoine, Frank G; Mazarico, Erwan; Sabaka, Terence J; Goossens, Sander J; Melosh, H Jay; Phillips, Roger J; Asmar, Sami W; Konopliv, Alexander S; Williams, James G; Sori, Michael M; Soderblom, Jason M; Miljković, Katarina; Andrews-Hanna, Jeffrey C; Nimmo, Francis; Kiefer, Walter S

2015-10-01

Observations from the Gravity Recovery and Interior Laboratory (GRAIL) mission indicate a marked change in the gravitational signature of lunar impact structures at the morphological transition, with increasing diameter, from complex craters to peak-ring basins. At crater diameters larger than ~200 km, a central positive Bouguer anomaly is seen within the innermost peak ring, and an annular negative Bouguer anomaly extends outward from this ring to the outer topographic rim crest. These observations demonstrate that basin-forming impacts remove crustal materials from within the peak ring and thicken the crust between the peak ring and the outer rim crest. A correlation between the diameter of the central Bouguer gravity high and the outer topographic ring diameter for well-preserved basins enables the identification and characterization of basins for which topographic signatures have been obscured by superposed cratering and volcanism. The GRAIL inventory of lunar basins improves upon earlier lists that differed in their totals by more than a factor of 2. The size-frequency distributions of basins on the nearside and farside hemispheres of the Moon differ substantially; the nearside hosts more basins larger than 350 km in diameter, whereas the farside has more smaller basins. Hemispherical differences in target properties, including temperature and porosity, are likely to have contributed to these different distributions. Better understanding of the factors that control basin size will help to constrain models of the original impactor population.

Pulling Marbles from a Bag: Deducing the Regional Impact History of the SPA Basin from Impact Melt Rocks

NASA Technical Reports Server (NTRS)

Cohen, Barbara A.; Coker, R. F.

2009-01-01

The South Pole-Aitken (SPA) basin is an important target for absolute age-dating. Vertical and lateral impact mixing ensures that regolith within SPA will contain rock fragments from SPA itself, local impact craters, and faraway giant basins. About 20% of the regolith at any given site is foreign [1, 2], but much of this material will be cold ejecta, not impact melt. We calculated the fraction of contributed impact melt using scaling laws to estimate the amount and provenance of impact melt, demonstrating that SPA melt is the dominant impact melt rock (>70%) likely to be present. We also constructed a statistical model to illustrate how many randomly-selected impact-melt fragments would need to be dated, and with what accuracy, to confidently reproduce the impact history of a site. A detailed impact history becomes recognizable after a few hundred to a thousand randomly-selected marbles, however, it will be useful to have more information (e.g. compositional, mineralogical, remote sensing) to group fragments. These exercises show that SPA melt has a high probability of being present in a scoop sample and that dating of a few hundred to a thousand impact-melt fragments will yield the impact history of the SPA basin.

The Mechanics of Impact Basin Formation: Comparisons between Modeling and Geophysical Observations

NASA Astrophysics Data System (ADS)

Stewart, S. T.

2010-12-01

Impact basins are the largest geologic structures on planetary surfaces. Single or multiple ring-shaped scarps or arcuate chains of massifs typically surround basin-sized craters (e.g., larger than about 300 km diameter on the moon [1]). Impact basins also possess central mass anomalies related to ejection of a portion of the crust (and mantle) and uplift of the mantle. I will discuss insights into the mechanics of impact basin formation derived from numerical simulations and focus on features that may be compared with gravity and topography data. The simulations of basin formation use the method of [2] with an improved rheological model that includes dynamic weakening of faults and more accurate treatment of the mantle solidus. Two-dimensional simulations of vertical impacts onto spherical planets utilize a central gravity field, and three-dimensional simulations of oblique impacts include a self-gravity calculation. During the opening and collapse of the transient crater, localization of strain leads to deformation features that are interpreted as deep faults through the lithosphere. Based on simulations of mantle-excavating impacts onto the moon and Mars with thermal gradients that intersect the solidus in the asthenosphere, the final impact structure has three major features: (i) an inner basin filled with melt and bounded by the folded lithosphere, (ii) a broad shallow terrace of faulted and translated lithosphere with an ejecta deposit, and (iii) the surrounding autochthonous lithosphere with radially thinning ejecta. The folded lithosphere is a complex structure that experiences translation inward and then outward again during collapse of the transient cavity. The uplifted mantle within this structure is overlain by a thin layer of hot crustal material. In addition to asymmetry in the excavated material, 45-degree impact events produce an asymmetric terrace feature. The principal observations for comparison to the calculations are the inferred locations of major ring structures (derived from topography and geologic mapping) and the crustal thickness and mantle topography (derived from gravity and topography) [see also 3]. Preliminary comparisons indicate that the simulations produce the major features in the observations. I will present detailed comparisons between simulations and observations for major basins on the moon, including South Pole-Aitken, for different initial lithospheric thicknesses and thermal gradients. [1] Spudis, P.D. (1993) The Geology of Multi-Ring Impact basins: Cambridge University Press. [2] Senft, L.E. and S.T. Stewart (2009) Earth and Planetary Science Letters 287, 471-482. [3] Lillis, R.J., et al. (2010) AGU Fall Meeting.

Noachian and Hesperian modification of the original Chryse impact basin topography

NASA Technical Reports Server (NTRS)

Stockman, Stephanie; Frey, Herbert

1994-01-01

We propose a new center (35.5 W, 32.5 N) and ring assignment for the original Chryse impact basin based on photogeologic mapping and re-examination of the published geology. Noachian features in the Chryse Planitia area are the best indicators of the original ancient multiringed impact structure. While other workers have centered the Chryse impact on the topographic low associated with Hesperian volcanic and fluvial deposits, we suggest that the center of the original Noachian-age excavation cavity was located 800 km farther NE, and the basin topography was significantly modified over time.

Chicxulub multiring impact basin - Size and other characteristics derived from gravity analysis

NASA Technical Reports Server (NTRS)

Sharpton, Virgil L.; Burke, Kevin; Camargo-Zanoguera, Antonio; Hall, Stuart A.; Lee, D. S.; Marin, Luis E.; Suarez-Reynoso, Gerardo; Quezada-Muneton, Juan M.; Spudis, Paul D.; Urrutia-Fucugauchi, Jaime

1993-01-01

The buried Chicxulub impact structure in Mexico, which is linked to the Cretaceous-Tertiary (K-T) boundary layer, may be significantly larger than previously suspected. Reprocessed gravity data over Northern Yucatan reveal three major rings and parts of a fourth ring, spaced similarly to those observed at multiring impact basins on other planets. The outer ring, probably corresponding to the basin's topographic rim, is almost 300 kilometers in diameter, indicating that Chicxulub may be one of the largest impact structures produced in the inner solar system since the period of early bombardment ended nearly 4 billion years ago.

MOLA Topography of Impact Basins in the Northern Hemisphere of Mars

NASA Technical Reports Server (NTRS)

Frey, Herbert; Sakimoto, S. E. H.; Roark, J. H.

1998-01-01

Coverage of the northern hemisphere of Mars by the Mars Orbiter Laser Altimeter (MOLA) during the aerobraking hiatus and the two Science Phasing Operation periods provides improved definition and characterization of large impact basins. Gridded MOLA data show the Utopia Basin has a pronounced bowl-like structure, as opposed to the interior rises suggested by the earlier USGS DEM. The elevation structure is concentric about the basin center as mapped by McGill. In particular, the proposed inner ring closely follows the -4 km contour over much of the southern, western and northwestern sides. Higher topography along portions of the dichotomy boundary aligns with the basin's outer ring. High topography in the polar region also occurs where the outer ring should lie, raising the possibility that perhaps some of the polar topography is due to basin structure as well as ice. Two MOLA passes near Phison Rupes provide evidence for a large "stealth" hole where Viking imagery show little evidence of any major structure. The 2 km deep, 600 km wide depression at 31OW, 3ON is as large as the Cassini impact basin 1000 km to the SW. While Cassini is easily recognized in image data, the "MOLA Hole" is not. If this depression is a deeply eroded and buried impact basin (as perhaps suggested by a decrease in the crater density and somewhat smoother terrain than in adjacent areas), it is not clear why it has managed to maintain its great depth. In Tempe at the dichotomy boundary a 300 km wide impact basin is revealed by pronounced bowl-like topography centered at 87W, 47N, even though only about 1/3 of the basin rim structure is obvious. The basin lies on a sloping boundary zone, with the more buried N rim up to 2 km below the rugged S rim. A similar N-S asymmetry in basin ring structure occurs for the much larger Isidis Basin, where the S rim rises 6 km but the subdued N rim rises barely 2 km above the floor. There is essentially no topographic expression of the main ring in the NE quadrant of Isidis where, if it exists, it lies below Hesperian-age plains.

Studying Basin Water Balance Variations at Inter- and Intra-annual Time Scales Based On the Budyko Hypothesis and GRACE Gravimetry Satellite Observations

NASA Astrophysics Data System (ADS)

Shen, H.

2017-12-01

Increasing intensity in global warming and anthropogenic activities has triggered significant changes over regional climates and landscapes, which, in turn, drive the basin water cycle and hydrological balance into a complex and unstable state. Budyko hypothesis is a powerful tool to characterize basin water balance and hydrological variations at long-term average scale. However, due to the absence of basin water storage change, applications of Budyko theory to the inter-annual and intra-annual time scales has been prohibited. The launch of GRACE gavimetry satellites provides a great opportunity to quantify terrestrial water storage change, which can be further introduced into the Budyko hypothesis to reveal the inter- and intra-annual response of basin water components under impacts of climate variability and/or human activities. This research targeted Hai River Basin (in China) and Murray-Darling Basin (in Australia), which have been identified with a continuous groundwater depletion trend as well as impacts by extreme climates in the past decade. This can help us to explore how annual or seasonal precipitation were redistributed to evapotranspiration and runoff via changing basin water storage. Moreover, the impacts of vegetation on annual basin water balance will be re-examined. Our results are expected to provide deep insights about the water cycle and hydrological behaviors for the targeted basins, as well as a proof for a consideration of basin water storage change into the Budyko model at inter- or intra-annual time steps.

Systematic impact assessment on inter-basin water transfer projects of the Hanjiang River Basin in China

NASA Astrophysics Data System (ADS)

Zhou, Yanlai; Guo, Shenglian; Hong, Xingjun; Chang, Fi-John

2017-10-01

China's inter-basin water transfer projects have gained increasing attention in recent years. This study proposes an intelligent water allocation methodology for establishing optimal inter-basin water allocation schemes and assessing the impacts of water transfer projects on water-demanding sectors in the Hanjiang River Basin of China. We first analyze water demands for water allocation purpose, and then search optimal water allocation strategies for maximizing the water supply to water-demanding sectors and mitigating the negative impacts by using the Standard Genetic Algorithm (SGA) and Adaptive Genetic Algorithm (AGA), respectively. Lastly, the performance indexes of the water supply system are evaluated under different scenarios of inter-basin water transfer projects. The results indicate that: the AGA with adaptive crossover and mutation operators could increase the average annual water transfer from the Hanjiang River by 0.79 billion m3 (8.8%), the average annual water transfer from the Changjiang River by 0.18 billion m3 (6.5%), and the average annual hydropower generation by 0.49 billion kW h (5.4%) as well as reduce the average annual unmet water demand by 0.40 billion m3 (9.7%), as compared with the those of the SGA. We demonstrate that the proposed intelligent water allocation schemes can significantly mitigate the negative impacts of inter-basin water transfer projects on the reliability, vulnerability and resilience of water supply to the demanding sectors in water-supplying basins. This study has a direct bearing on more intelligent and effectual water allocation management under various scenarios of inter-basin water transfer projects.

The economic impact on the forest sector of critical habitat delineation for salmon in the Columbia and Snake River basins.

Treesearch

R.W. Haynes; N.A. Bolon; D.T. Hormaechea

1992-01-01

Economic implications of critical habitat designation (CHD) for salmon in the Columbia River basin were estimated in advance of actual designation and recovery plan development. Economic impacts on Pacific, Northwest, Intermountain, and Northern Region National Forests' range, recreation, timber, and mineral programs in the Columbia and Snake River basins were...

Volume of Impact Melt Generated by the Formation of the South Pole-Aitken Basin

NASA Technical Reports Server (NTRS)

Petro, Noah E.

2011-01-01

The South Pole-Aitken Basin (SPA) is the largest, deepest, and oldest identified basin on the Moon and as such contains surfaces that are unique due to their age, composition, and depth of origin in the lunar crust [1-5] (Figure 1). SPA has been a target of intense interest as an area for robotic sample return in order to determine the age of the basin and the composition and origin of its interior [6-8]. In response to this interest there have been several efforts to estimate the likely provenance of regolith material within central SPA [9-12]. These model estimates suggest that, despite the formation of basins and craters following SPA, the regolith within SPA is dominated by locally derived material. An assumption of these models has been that the locally derived material is primarily SPA impact-melt as opposed to local basement material (e.g. unmelted lower crust). However, the definitive identification of SPA derived impact melt on the basin floor, either by remote sensing [5, 13] or via photogeology [2, 14] is extremely difficult due to the number of subsequent impacts and volcanic activity [4].

Identifying and Characterizing Impact Melt Outcrops in the Nectaris Basin

NASA Technical Reports Server (NTRS)

Cohen, B. A.; Lawerence, S. J.; Petro, N. E.; Bart, G. D.; Clegg-Watkins, R. N.; Denevi, B. W.; Ghent, R. R.; Klima, R. L.; Morgan, G. A.; Spudis, P. D.;

The Argyre Region as a Prime Target for in situ Astrobiological Exploration of Mars.

PubMed

Fairén, Alberto G; Dohm, James M; Rodríguez, J Alexis P; Uceda, Esther R; Kargel, Jeffrey; Soare, Richard; Cleaves, H James; Oehler, Dorothy; Schulze-Makuch, Dirk; Essefi, Elhoucine; Banks, Maria E; Komatsu, Goro; Fink, Wolfgang; Robbins, Stuart; Yan, Jianguo; Miyamoto, Hideaki; Maruyama, Shigenori; Baker, Victor R

2016-02-01

At the time before ∼3.5 Ga that life originated and began to spread on Earth, Mars was a wetter and more geologically dynamic planet than it is today. The Argyre basin, in the southern cratered highlands of Mars, formed from a giant impact at ∼3.93 Ga, which generated an enormous basin approximately 1800 km in diameter. The early post-impact environment of the Argyre basin possibly contained many of the ingredients that are thought to be necessary for life: abundant and long-lived liquid water, biogenic elements, and energy sources, all of which would have supported a regional environment favorable for the origin and the persistence of life. We discuss the astrobiological significance of some landscape features and terrain types in the Argyre region that are promising and accessible sites for astrobiological exploration. These include (i) deposits related to the hydrothermal activity associated with the Argyre impact event, subsequent impacts, and those associated with the migration of heated water along Argyre-induced basement structures; (ii) constructs along the floor of the basin that could mark venting of volatiles, possibly related to the development of mud volcanoes; (iii) features interpreted as ice-cored mounds (open-system pingos), whose origin and development could be the result of deeply seated groundwater upwelling to the surface; (iv) sedimentary deposits related to the formation of glaciers along the basin's margins, such as evidenced by the ridges interpreted to be eskers on the basin floor; (v) sedimentary deposits related to the formation of lakes in both the primary Argyre basin and other smaller impact-derived basins along the margin, including those in the highly degraded rim materials; and (vi) crater-wall gullies, whose morphology points to a structural origin and discharge of (wet) flows.

The geologic history of the Moon

USGS Publications Warehouse

Wilhelms, Don E.; with sections by McCauley, John F.; Trask, Newell J.

1987-01-01

More than two decades of study have established the major features of lunar geologic style and history. The most numerous and significant landforms belong to a size-morphology series of simple craters, complex craters, and ringed basins that were formed by impacts. Each crater and basin is the source of primary ejecta and secondary craters that, collectively, cover the entire terra. The largest impacts thinned, weakened, and redistributed feldspathic terracrustal material averaging about 75 km in thickness. Relatively small volumes of basalt, generated by partial remelting of mantle material, were erupted through the thin subbasin and subcrater crust to form the maria that cover 16 percent of the lunar surface. Tectonism has modified the various stratigraphic deposits relatively little; most structures are confined to basins and large craters. This general geologic style, basically simple though complex in detail, has persisted longer than 4 aeons (1 aeon = 109 yr). Impacts began to leave a visible record about 4.2 aeons ago, after the crust and mantle had differentiated and the crust had solidified. At least 30 basins and 100 times that many craters larger than 30 km in diameter were formed before a massive impact created the Nectaris basin about 3.92 aeons ago. Impacts continued during the ensuing Nectarian Period at a lesser rate, whereas volcanism left more traces than during pre-Nectarian time. The latest basin-forming impacts created the giant and still-conspicuous Imbrium and Orientale basins during the Early Imbrian Epoch, between 3.85 and 3.80 aeons ago. The rate of crater-forming impacts continued to decline during the Imbrian Period. Beginning in the Late Imbrian Epoch, mare-basalt flows remained exposed because they were no longer obscured by many large impacts. The Eratosthenian Period (3.2-1.1 aeons ago) and the Copernican Period (1.1 aeons ago to present) were times of lesser volcanism and a still lower, probably constant impact rate. Copernican impacts created craters whose surfaces have remained brighter and topographically crisper than those of the more ancient lunar features.

Geologic support for the putative Borealis basin (Mega-Impact) on Mars

NASA Astrophysics Data System (ADS)

Bleamaster, L. F.

2008-12-01

A series of recent papers (all in Nature v. 453) using Martian gravity and topography [Andrews-Hanna et al., 2008], 3-D hydrodynamic simulations [Marinova et al., 2008], and 2-D hydrocode models [Nimmo et al., 2008] have eloquently reintroduced the single mega-impact hypothesis for the formation of the Martian hemispheric dichotomy boundary. Although geophysical models often return non-unique solutions, the coalition front presented by these three independent methods to test such a hypothesis lends credibility and demands further evaluation. The central tenet of these works is the proposition that an elliptical basin (long axis 10,600km, ellipticity 1.25) centered at 67N, 208E marks the pre-Tharsis crustal thickness transition and thus the real dichotomy boundary. Evaluation of this new boundary with respect to the geologic record offers new avenues, especially since geologic tests of the mega-impact hypothesis have mostly proved inconclusive because of Mars' multi-stage and multi-process geologic history. Within this survey, a slightly larger ellipse with a long axis of 12,500 km, ellipticity of 1.48, and centered at 65.3N, 250E expands the putative Borealis impact basin (which does not necessarily represent the transient or final impact cavity dimensions, but defines a potential 'affected zone') while maintaining agreement with the original observations with respect to gravity and topography. The 'affected zone' can be defined by basement structure that may become susceptible to later deformation, or it may in fact have been the paleo- topographic expression of the basin. By expanding the overall area (nearly twice the area of the original mega-impact basin proposed by Wilhelms and Squyres in 1984) several geologic features become significant in evaluating the mega-impact story. 1) Valles Marineris is concentric to the putative basin interior and parallels the ellipse margin suggesting that it is the structural manifestation of localized crustal relaxation of the Tharsis volcanic pile over pre-existing basement structure related to Borealis basin subsidence. The present day Valles Marineris may actually represent the 'missing portion' of the original crustal dichotomy trace underneath Tharsis. 2) The 'great faults' (Connerney et al., 2005) that offset the magnetic field pattern radiate from near the center of the putative basin, again suggesting basement structural control related to basin formation. 3) The mysterious Medusa Fossae Formation is completely enclosed within the basin margin and the units' southern contacts fall within 5 km of the same elliptical trace that bisects central Valles Marineris. 4) Chaos regions at the eastern end of Valles Marineris are wholly contained within the basin margin and suggest some kind of marginal control on their locations. 5) Valley network (channel) densities sharply increase outside the basin and are truncated by the Borealis ellipse. Integrating these and other geologic observations (still ongoing) with the newly formulated geophysical methods suggests that a single mega-impact is reemerging as a viable and perhaps preferred mechanism for dichotomy formation.

78 FR 15973 - Notice of Public Scoping Meetings for the Pojoaque Basin Regional Water System Environmental...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-03-13

... Pojoaque Basin Regional Water System Environmental Impact Statement, New Mexico AGENCY: Bureau of... Environmental Policy Act of 1969, as amended, the Bureau of Reclamation is preparing an environmental impact... document, alternatives, concerns, and issues to be addressed in the environmental impact statement. DATES...

78 FR 65609 - Medicine Bow-Routt National Forests and Thunder Basin National Grassland; Wyoming; Thunder Basin...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-11-01

... National Grassland; Wyoming; Thunder Basin National Grassland Prairie Dog Amendment Environmental Impact... alternatives will be analyzed in the Thunder Basin National Grassland Prairie Dog Amendment EIS. The EIS will... Basin National Grassland Prairie Dog Amendment. The Open House/ Presentation meetings will be held on...

Groundwater quality assessment/corrective action feasibility plan: New TNX Seepage Basin

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nichols, R.L.

1989-12-05

The New TNX Seepage Basin is located across River Road east of the TNX Area at the Savannah River Site. Currently the basin is out of service and is awaiting closure in accordance with the Consent Decree settled under Civil Act No. 1:85-2583. Groundwater monitoring data from the detection monitoring network around the New TNX Seepage Basin was recently analyzed using South Carolina Hazardous Waste Management Regulations R.61-79.264.92 methods to determine if groundwater downgradient of the New TNX Seepage Basin had been impacted. Results from the data analysis indicate that the groundwater has been impacted by inorganic constituents with nomore » associated health risks. The impacts resulting from elevated levels of inorganic constituents, such as Mn, Na, and Total PO{sub 4} in the water table, do not pose a threat to human health and the environment.« less

Changing sediment budget of the Mekong: Cumulative threats and management strategies for a large river basin.

PubMed

Kondolf, G Mathias; Schmitt, Rafael J P; Carling, Paul; Darby, Steve; Arias, Mauricio; Bizzi, Simone; Castelletti, Andrea; Cochrane, Thomas A; Gibson, Stanford; Kummu, Matti; Oeurng, Chantha; Rubin, Zan; Wild, Thomas

2018-06-01

Two decades after the construction of the first major dam, the Mekong basin and its six riparian countries have seen rapid economic growth and development of the river system. Hydropower dams, aggregate mines, flood-control dykes, and groundwater-irrigated agriculture have all provided short-term economic benefits throughout the basin. However, it is becoming evident that anthropic changes are significantly affecting the natural functioning of the river and its floodplains. We now ask if these changes are risking major adverse impacts for the 70 million people living in the Mekong Basin. Many livelihoods in the basin depend on ecosystem services that will be strongly impacted by alterations of the sediment transport processes that drive river and delta morpho-dynamics, which underpin a sustainable future for the Mekong basin and Delta. Drawing upon ongoing and recently published research, we provide an overview of key drivers of change (hydropower development, sand mining, dyking and water infrastructures, climate change, and accelerated subsidence from pumping) for the Mekong's sediment budget, and their likely individual and cumulative impacts on the river system. Our results quantify the degree to which the Mekong delta, which receives the impacts from the entire connected river basin, is increasingly vulnerable in the face of declining sediment loads, rising seas and subsiding land. Without concerted action, it is likely that nearly half of the Delta's land surface will be below sea level by 2100, with the remaining areas impacted by salinization and frequent flooding. The threat to the Delta can be understood only in the context of processes in the entire river basin. The Mekong River case can serve to raise awareness of how the connected functions of river systems in general depend on undisturbed sediment transport, thereby informing planning for other large river basins currently embarking on rapid economic development. Copyright © 2017 Elsevier B.V. All rights reserved.

Colorado River basin sensitivity to disturbance impacts

NASA Astrophysics Data System (ADS)

Bennett, K. E.; Urrego-Blanco, J. R.; Jonko, A. K.; Vano, J. A.; Newman, A. J.; Bohn, T. J.; Middleton, R. S.

2017-12-01

The Colorado River basin is an important river for the food-energy-water nexus in the United States and is projected to change under future scenarios of increased CO2emissions and warming. Streamflow estimates to consider climate impacts occurring as a result of this warming are often provided using modeling tools which rely on uncertain inputs—to fully understand impacts on streamflow sensitivity analysis can help determine how models respond under changing disturbances such as climate and vegetation. In this study, we conduct a global sensitivity analysis with a space-filling Latin Hypercube sampling of the model parameter space and statistical emulation of the Variable Infiltration Capacity (VIC) hydrologic model to relate changes in runoff, evapotranspiration, snow water equivalent and soil moisture to model parameters in VIC. Additionally, we examine sensitivities of basin-wide model simulations using an approach that incorporates changes in temperature, precipitation and vegetation to consider impact responses for snow-dominated headwater catchments, low elevation arid basins, and for the upper and lower river basins. We find that for the Colorado River basin, snow-dominated regions are more sensitive to uncertainties. New parameter sensitivities identified include runoff/evapotranspiration sensitivity to albedo, while changes in snow water equivalent are sensitive to canopy fraction and Leaf Area Index (LAI). Basin-wide streamflow sensitivities to precipitation, temperature and vegetation are variable seasonally and also between sub-basins; with the largest sensitivities for smaller, snow-driven headwater systems where forests are dense. For a major headwater basin, a 1ºC of warming equaled a 30% loss of forest cover, while a 10% precipitation loss equaled a 90% forest cover decline. Scenarios utilizing multiple disturbances led to unexpected results where changes could either magnify or diminish extremes, such as low and peak flows and streamflow timing, dependent on the strength and direction of the forcing. These results indicate the importance of understanding model sensitivities under disturbance impacts to manage these shifts; plan for future water resource changes and determine how the impacts will affect the sustainability and adaptability of food-energy-water systems.

Security Blanket

NASA Technical Reports Server (NTRS)

2006-01-01

2 June 2006 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows material on the floor of a crater in Noachis Terra, west of Hellas Planitia. Windblown features, both the large, dark-toned sand dunes and smaller, light-toned ripples, obscure and perhaps, protect portions of the crater floor from further modification by erosional processes.

Location near: 45.4oS, 331.2oW Image width: 3 km (1.9 mi) Illumination from: upper left Season: Southern Summer

Winter Frost and Fog

NASA Technical Reports Server (NTRS)

2005-01-01

This somewhat oblique blue wide angle Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows the 174 km (108 mi) diameter crater, Terby, and its vicinity in December 2004. Located north of Hellas, this region can be covered with seasonal frost and ground-hugging fog, even in the afternoon, despite being north of 30oS. The subtle, wavy pattern is a manifestation of fog.

Location near: 28oS, 286oW Illumination from: upper left Season: Southern Winter

On Dams in the Amazon Basin, Teleconnected Impacts, and Neighbors Unaware of the Damage to their Natural Resources and Assets.

NASA Astrophysics Data System (ADS)

Latrubesse, E. M.; Park, E.

2017-12-01

In a recent study, Latrubesse et al., (2017) demonstrated that the accumulated negative environmental effects of more than one hundred existing dams and at least 288 proposed dams, if constructed, will trigger massive hydrophysical and biotic disturbances that will affect the Amazon basin's floodplains, estuary and sediment plume. The authors introduced a Dam Environmental Vulnerability Index (DEVI) to quantify the current and potential impacts of dams in the basin. The current and potential vulnerabilities of different regions of the Amazon basin was assessed, and the results highlighted the need for a more efficient and integrative legal framework involving all nine countries of the basin in an anticipatory assessment to minimize the negative socio-environmental and biotic impacts of hydropower developments. Here we present expanded information on the potential impacts of dams in the lower Amazon and the northeast Atlantic coast of South America, and revisit our proposed integrative strategies for basin management which are based on the adaptation and functionality of the institutional and legal framework already existing in the Amazon countries. Participative strategies involving members from the Amazon Cooperation Treaty Organization (ACTO) countries, and additional members (for example, France), such as the creation of a basin committee -as defined by the Brazilian Law of Waters of Brazil-, and the creation of an Amazon Basin Panel allowing the participation of scientists that could have a policy-relevant role but should be not policy-prescriptive, are also discussed. ReferencesLatrubesse, E., Arima E. Dunne T., Park E., Baker V, Horta F.,Wight, C., Wittmann F., Zuanon, J., Baker P., Ribas C, Norgaard R., Filizola N., Ansar A., Flyvbjerg B., Stevaux, J. 2017. Damming the rivers of the Amazon basin. Nature, 546, 363-369.

Magnetic Anomalies Within Lunar Impact Basins: Constraints on the History of the Lunar Dynamo

NASA Astrophysics Data System (ADS)

Richmond, N. C.; Hood, L. L.

2011-12-01

Previous work has shown that lunar crustal magnetization has a combination of origins including shock remanent magnetization in transient magnetic fields and thermoremanent magnetization in a steady core dynamo magnetic field (e.g., Hood and Artemieva, Icarus, 2008; Richmond and Hood, JGR, 2008; Garrick-Bethell et al., Science, 2009; Hood, Icarus, 2011). In particular, magnetic anomalies within the interiors of lunar impact basins and large craters provide a potentially valuable means of constraining the history of the former dynamo (Halekas et al., MAPS, 2003; Hood, 2011). These anomalies likely have a thermoremanent origin owing to high subsurface temperatures reached at the time of impact and therefore require a long-lived, steady magnetic field to explain their magnetization. Central anomalies have previously been confirmed to be present using Lunar Prospector magnetometer (LP MAG) data within several Nectarian-aged basins (Moscoviense, Mendel-Rydberg, Crisium, and Humboldtianum), implying that a dynamo existed during this lunar epoch (Hood, 2011). Here, we further analyze low altitude LP MAG data for several additional basins, ranging in age from Nectarian to Imbrian. Results indicate that magnetic anomalies with a probable basin-related origin are present within at least two additional Nectarian-aged basins (Serenitatis and Humorum) and one Imbrian-aged basin (Schrodinger). No discernible anomalies are present within the largest Imbrian-aged basins, Imbrium and Orientale. While there is uncertainty regarding the age of the Schrodinger basin, it has been reported to be slightly more recent than Imbrium (Wilhelms, 1984). Our initial interpretation is therefore that a dynamo likely existed during the Imbrian epoch. The absence of anomalies within Imbrium and Orientale can be explained by insufficient conditions for acquisition of strong magnetization (e.g., inadequate concentrations of efficient remanence carriers) following these relatively large impacts.

Moonrise: Sampling the South Pole-Aitken Basin to Address Problems of Solar System Significance

NASA Technical Reports Server (NTRS)

Zeigler, R. A.; Jolliff, B. L.; Korotev, R. L.; Shearer, C. K.

2016-01-01

A mission to land in the giant South Pole-Aitken (SPA) Basin on the Moon's southern farside and return a sample to Earth for analysis is a high priority for Solar System Science. Such a sample would be used to determine the age of the SPA impact; the chronology of the basin, including the ages of basins and large impacts within SPA, with implications for early Solar System dynamics and the magmatic history of the Moon; the age and composition of volcanic rocks within SPA; the origin of the thorium signature of SPA with implications for the origin of exposed materials and thermal evolution of the Moon; and possibly the magnetization that forms a strong anomaly especially evident in the northern parts of the SPA basin. It is well known from studies of the Apollo regolith that rock fragments found in the regolith form a representative collection of many different rock types delivered to the site by the impact process (Fig. 1). Such samples are well documented to contain a broad suite of materials that reflect both the local major rock formations, as well as some exotic materials from far distant sources. Within the SPA basin, modeling of the impact ejection process indicates that regolith would be dominated by SPA substrate, formed at the time of the SPA basin-forming impact and for the most part moved around by subsequent impacts. Consistent with GRAIL data, the SPA impact likely formed a vast melt body tens of km thick that took perhaps several million years to cool, but that nonetheless represents barely an instant in geologic time that should be readily apparent through integrated geochronologic studies involving multiple chronometers. It is anticipated that a statistically significant number of age determinations would yield not only the age of SPA but also the age of several prominent nearby basins and large craters within SPA. This chronology would provide a contrast to the Imbrium-dominated chronology of the nearside Apollo samples and an independent test of the timing of the lunar cataclysm.

Magnetic Signatures of Nectarian-Aged Lunar Basin-Forming Impacts: Probable Evidence for a Former Core Dynamo

NASA Astrophysics Data System (ADS)

Hood, Lon

2010-05-01

Previous analyses of Lunar Prospector magnetometer (MAG) and electron reflectometer (ER) data have shown that impact processes played an important role in producing the observed crustal magnetization. In particular, the largest areas of strong anomalies occur antipodal to the youngest large basins and correlative studies indicate that basin ejecta materials are important anomaly sources. Models suggest that transient fields generated by the expansion of impact vapor-melt clouds in the presence of an initial solar wind magnetic field are sufficient to explain the antipodal anomalies (Hood and Artemieva, Icarus, v. 193, p. 485, 2008). However, analyses of ER data have also shown that some anomalies are present within Nectarian-aged basins including Moscoviense, Mendel-Rydberg, and Crisium (Halekas et al., Meteorit. Planet. Sci., v. 38, p. 565, 2003). These latter anomalies could be due either to thermoremanence (TRM) in impact melt or to shock remanence in the central uplift. The former interpretation would require a long-lived, steady magnetizing field, consistent with a core dynamo, while the latter interpretation could in principle be explained by an impact-generated field. Here, LP MAG data are applied to produce more detailed regional maps of magnetic anomalies within selected Nectarian basins. Anomalies within the Crisium basin, in particular, are located inside the inner rim edges and are clearly genetically associated with the basin (rather than being due to ejecta from younger basins superposed on Crisium). An analysis of the vector field components shows that the directions of magnetization of the two main sources are close to parallel within the errors of the modeling. These anomalies are therefore most probably due to TRM of impact melt that cooled in a steady, large-scale field. In addition, the paleomagnetic pole position calculated for the strongest and most isolated anomaly lies close to the present rotational pole. Assuming no true polar wander since the Crisium impact and that the lunar dynamo behaved similarly to presently existing terrestrial planet dynamos, they are therefore consistent with the existence of a lunar dynamo field.

Option contracts for allocating water in inter-basin transfers: the case of the Tagus-Segura Transfer in Spain

NASA Astrophysics Data System (ADS)

Rey, Dolores; Garrido, Alberto; Calatraba, Javier

2014-05-01

Users in the Mediterranean region face significant water supply risks. Water markets mechanisms can provide flexibility to water systems run in tight situations. The largest water infrastructure in the Iberian Peninsula connects the Segura and Tagus Basins. Stakeholders and politicians in the Tagus Basin have asked that water transfers between the two basins be eventually phased out. The need to increase the statutory minimum environmental flow in the middle Tagus and to meet new urban demands is going to result in a redefinition of the Transfer's management rules, leading to a reduction in the transferable volumes. To minimise the consequences of such restrictions to irrigators in the Segura Basin who depend on the transferred volumes, we propose the establishment of water option contracts between both basins that represents an institutional innovation with respect to previous inter-basin spot market experiences. Based on the draft of the new Tagus Basin Plan, we propose both a modification of the Transfer's management rule and an innovative inter-basin option contract. The main goal of the paper is to define this contract and evaluate it with respect to non-market scenarios. We also assess the resulting impact on environmental flows in the Tagus River and water availability for users in the Segura Basin, together with the economic impacts of such contract on both basins. Our results show that the proposed option contract would reduce the impact of a change in the transfer's management rule, and reduce the supply risks of the recipient area. Keywords: environmental flow, inter-basin transfer, option contracts, Tagus-Segura, water markets, water supply reliability.

New morphological mapping and interpretation of ejecta deposits from Orientale Basin on the Moon

NASA Astrophysics Data System (ADS)

Morse, Zachary R.; Osinski, Gordon R.; Tornabene, Livio L.

2018-01-01

Orientale Basin is one of the youngest and best-preserved multi-ring impact basins in the Solar System. The structure is ∼950 km across and is located on the western edge of the nearside of the Moon. The interior of the basin, which possesses three distinct rings and a post-impact mare fill, has been studied extensively using modern high-resolution datasets. Exterior to these rings, Orientale has an extensive ejecta blanket that extends out radially for at least 800 km from the basin rim in all directions and covers portions of both the nearside and farside of the Moon. These deposits, known as the Hevelius Formation, were first mapped using photographic data from the Lunar Orbiter IV probe. In this study, we map in detail the morphology of each distinct facies observed within the Orientale ejecta blanket using high resolution Lunar Reconnaissance Orbiter (LRO) Wide Angle Camera (WAC) and Narrow Angle Camera (NAC) images and Lunar Orbiter Laser Altimeter (LOLA) elevation data. We identified 5 unique facies within the ejecta blanket. Facies A is identified as a region of hummocky plains located in a low-lying topographic region between the Outer Rook and Cordillera rings. This facies is interpreted to be a mix of crater-derived impact melt and km-scale blocks of ballistic ejecta and host rock broken up during the modification stage and formation of the Cordillera ring. Facies B is an inner facies marked by radial grooves extending outward from the direction of the basin center. This facies is interpreted as the continuous ballistic ejecta blanket. Facies C consists of inner and outer groupings of flat smooth-surfaced deposits isolated in local topographic lows. Facies D displays characteristic sinuous ridges and lobate extensions. Facies C and D are interpreted to be impact melt-rich materials, which manifest as flows and ponds. Our observations suggest that these facies were emplaced subsequent to the ballistic ejecta blanket - most likely during the modification stage of crater formation - and flowed and ponded in topographically low-lying regions. Facies E consists of distinct crater chains emanating radially from the basin center and extending from ∼700 to ∼1000 km from the center of Orientale. This facies is considered to be chains of secondary craters formed from large blocks of ballistic ejecta. Our mapping effort shows that the individual ejecta facies were influenced and controlled to varying degrees by pre-existing slopes and topography. At the basin scale, the overall downslope direction toward the lunar lowlands to the east and southeast of the basin center resulted in large impact melt flows 100's of kilometers in length, while the regional upslope trends in the west and northwest inhibited the development of extensive impact melt flows. On a smaller scale it can be observed that ground-hugging ejecta collected behind and flowed around high topographic obstacles while diverting into topographic low regions (e.g., around uplifted pre-existing crater rims, but down into pre-existing crater floors). The dispersion of the various ejecta facies mapped here also indicates both a direction and an angle for the impact event that formed Orientale Basin. The bilateral distribution of both ballistic and impact melt-rich ejecta deposits across a line running northeast - southwest suggests the impact occurred from the northeast toward the southwest. Careful mapping of the secondary impact crater chains (Facies E) shows the development of a ;forbidden zone; lacking these impacts to the northeast as well as a concentration of the longest secondary crater chains to the northwest and southeast, perpendicular to the aforementioned line of bilateral ejecta distribution. This distribution of secondary impact craters contrasts with the circularity of the basin and suggests that Orientale Basin was formed by ∼ 25-45° impact from the northeast.

Estimating different eruptive style volcanic areas of Mars from NASA Martian Meteorites Compendium data

NASA Astrophysics Data System (ADS)

Mari, Nicola; Verrino, Miriam

2016-04-01

The geomorphological characteristics of the Martian surface suggest that both effusive and explosive eruptive behaviour occurred. We investigated whether data about magma viscosity could be extrapolated from Mars SNCs (Shergotty, Nakhla, and Chassigny classes) meteorites, by using available geochemical and petrographic data from the NASA Martian Meteorites Compendium. Viscosity was used to characterize how eruptive style could change in different volcanic regions of planet Mars. Data about composition and crystallinity of 41 SNCs meteorites were used and classified, avoiding meteorites with poor/incomplete database. We assumed Mars as a one-plate planet, fO2 = QFM, and H2O wt% = 0 for each sample. Collected data from the Mars Global Surveyor Thermal Emission Spectrometer (MGS TES) identified the source regions for almost all the studied SNCs meteorites. As input for thermodynamic simulations we first needed to find the depth and pressure of the magmatic source for each meteorite sample through available Thermal Emission Imaging System (THEMIS). Data about average surface temperatures was used to establish whether a magmatic source is shallow or deep. Successively, we found the magma source depth (and pressure) by using the relationship with the heights of the volcanic edifice. The subsolidus equilibration temperatures found through petrologic softwares were used to calculate viscosity. Results indicate a crystallization temperature in a range from 1,120°C to 843°C, follow by a variation in viscosity from 101,43 to 105,97 Pa s. Viscosity seems to be higher in Tharsis, Elysium, Amazonis, and Syrtis Major regions than the remnant areas. According to past experimental studies about magma viscosity, we classified the eruptive style into effusive (101-103,5 Pa s), intermediate (103,5-104,5 Pa s), and explosive (104,5-106 Pa s). The Hellas Basin, Argyre Basin, Ganges Chasma, Eos Chasma, and Nili Fossae regions show an eruptive behaviour between effusive and intermediate, while the Tharsis, Elysium, Amazonis, Syrtis Major, and Terra Tyrrhena regions have a more explosive eruptive style, even if effusive/intermediate activity also occur. Our results seems to be in accord with the Martian geomorphology of the cited areas.

Assessing and managing water scarcity within the Nile River Transboundary Basin

NASA Astrophysics Data System (ADS)

Butts, M. B.; Wendi, D.; Jessen, O. Z.; Riegels, N. D.

2012-04-01

The Nile Basin is the main source of water in the North Eastern Region of Africa and is perhaps one of the most critical river basins in Africa as the riparian countries constitute 40% of the population on the continent but only 10% of the area. This resource is under considerable stress with rising levels of water scarcity, high population growth, watershed degradation, and loss of environmental services. The potential impacts of climate change may significantly exacerbate this situation as the water resources in the Nile Basin are critically sensitive to climate change (Conway, Hanson, Doherty, & Persechino, 2007). The motivation for this study is an assessment of climate change impacts and adaptation potential for floods and droughts within the UNEP project "Adapting to climate change induced water stress in the Nile River Basin", supported by SIDA. This project is being carried out as collaboration between DHI, the UK Met Office, and the Nile Basin Initiative (NBI). The Nile Basin exhibits highly diverse climatological and hydrological characteristics. Thus climate change impacts and adaptive capacity must be addressed at both regional and sub-basin scales. While the main focus of the project is the regional scale, sub-basin scale modelling is required to reflect variability within the basin. One of the major challenges in addressing this variability is the scarcity of data. This paper presents an initial screening modelling study of the water balance of the Nile Basin along with estimates of expected future impacts of climate change on the water balance. This initial study is focussed on the Ethiopian Highlands and the Lake Victoria regions, where the impact of climate change on rainfall is important. A robust sub-basin based monthly water balance model is developed and applied to selected sub-basins. The models were developed and calibrated using publicly available data. One of the major challenges in addressing this variability within the basin is the scarcity of spatial data and the results for the Kagera sub-basin show that it is important to represent the spatial distribution of the hydro-geographic characteristics such as rainfall, soil type, etc., in order to develop a reasonable representation of the water balance. These initial results show that the changes in the water balance and flow regime under climate change exhibit large uncertainty. From an examination the flow duration curves, however, there seems to be a consensus, based on an ensemble of climate projections, that flows will increase slightly the short term (2011-2030) and decrease significantly in the long term 2080-2099. The large uncertainties together with the natural variability in the Nile suggest that there is a strong need to maximise adaptive capacity with the region.

Urbanization Impacts on Flooding in the Kansas River Basin and Evaluation of Wetlands as a Mitigation Measure

EPA Science Inventory

This study evaluates the impacts of future land use changes on flooding in the Kansas River Basin. It also studies the impacts of wetlands on flood reduction. The study presents Hydrologic Engineering Centers-Hydrologic Modeling System (HEC-HMS) based runoff modeling and River A...

Previously Unrecognized Large Lunar Impact Basins Revealed by Topographic Data

NASA Technical Reports Server (NTRS)

Frey, Herbert V.

2008-01-01

The discovery of a large population of apparently buried impact craters on Mars, revealed as Quasi- Circular Depressions (QCDs) in Mars Orbiting Laser Altimeter (MOLA) data [1,2,3] and as Circular Thin Areas (CTAs) [4] in crustal thickness model data [5] leads to the obvious question: are there unrecognized impact features on the Moon and other bodies in the solar system? Early analysis of Clementine topography revealed several large impact basins not previously known [6,7], so the answer certainly is "Yes." How large a population of previously undetected impact basins, their size frequency distribution, and how much these added craters and basins will change ideas about the early cratering history and Late Heavy Bombardment on the Moon remains to be determined. Lunar Orbiter Laser Altimeter (LOLA) data [8] will be able to address these issues. As a prelude, we searched the state-of-the-art global topographic grid for the Moon, the Unified Lunar Control Net (ULCN) [9] for evidence of large impact features not previously recognized by photogeologic mapping, as summarized by Wilhelms [lo].

Proposed Mars Surveyor Landing Sites in Northern Meridiani Sinus, Southern Elysium Planitia, and Argyre Planitia

NASA Technical Reports Server (NTRS)

Parker, T. J.; Edgett, K. S.

1998-01-01

Our objective is to propose two landing sites that the Mars Surveyor 2001 Lander and Athena Rover could go to on Mars that should meet the safety requirements of the spacecraft landing system and optimize surface operations (chiefly driven by power and communications requirements). An additional site within Argyre Planitia, initially proposed by Parker to the Mars Surveyor Landing Site program, is also proposed for potential consideration for post-2001 missions to Mars, as it is well outside the current latitude limits for the Athena Rover. All three sites are designed to be situated as close to a diversity of geologic units within a few kilometers of the landing site so that diversity can be placed in a geologic context. This objective is very different from the Mars Pathfinder requirement to land at a site with a maximum chance for containing a diversity of rocks within a few tens of meters of the lander. That requirement was driven by the Sojourner mobility limit of a few tens of meters. It can be argued that the Athena project, with its much larger mobility capability, might actually want to avoid such a site, because placing collected samples in geologic context would be difficult. While it has been argued, both before and after the Mars Pathfinder landing, that the provenance for local blocks may be determined by orbiter spectra, primarily from the MGS TES instrument, our ability to do so has yet to be demonstrated. Indeed, several months after conclusion of the Pathfinder mission, we have yet to reach a consensus on the composition of local materials. Our primary data set for selecting a landing site within the latitude and elevation constraints of the 2001 mission is the Viking Orbiter image archive. The site must be selected to place the landing ellipse so as to avoid obvious hazards, such as steep slopes, large or numerous craters, or abundant large knobs. For this purpose, we chose a resolution limit of better than 50 m/pixel. This necessarily excludes from the present study images from current and future orbiter spacecraft, until such data does become readily available. Within each proposed region, it may be possible to identify additional sites once these data become available. Second, the fine-component thermal inertia data, should be greater than about 5 or 6 cgs Units (10(exp -3) cal/sq cm s(exp -0.5)/K). Low thermal inertias imply dusty environments, which could pose a mobility hazard. Similarly, the albedo of the site should not be particularly high, which would also suggest dusty surfaces. Low albedos are preferred, as they often coincide with low Viking red:violet ratios and indicate less dusty surfaces. Next, the Modeled Block Abundance should also not be too high or too low. Based on the Viking Lander and Mars Pathfinder experiences, percentages of blocks should be on the order of 5-25%. Too many blocks could pose a hazard to the landing and mobility. Too few blocks could also indicate a dusty surface. Primary Landing Site: Northern Meridiani Sinus (Proposed by T. J. Parker and K., S. Edgett) Vital Statistics: (1) Latitude, Longitude: 0-3 N, 350-2 W. *Elevation (Viking): about0.5-1.5 Ian. (2) Viking Orbiter Image coverage: Excellent coverage by 15 - 25 m/pixel images (orbits 709A and 410B). Possible stereo coverage in region where two orbits overlap (probably small parallax angle, as these orbits are not listed in NASA Contractor Report 3501) (3) Albedo: about .18 -.26 (4) Block Abundance: 5-26% (5)Fine-Component Thermal Inertia: 5-9 cgs units This region consists of bright deposits similar to those described by Edgett et al, that also lie within a prominent dark albedo region. These deposits are flat-lying, to such a degree that they ramp against topography rather than draping over it. This led Edgett and Parker to suggest that they may be subaqueous sediments, possibly lacustrine or marine evaporites, laid down sometime from the late Noachian to middle Hesperian (age determination pending crater counts). A contact between this material and elevated, dissected highlands to the south was identified , and is described by Edgett et al. Our desire in proposing this landing site is to sample the edge of this deposit where it has been exposed through etching, presumably eolian deflation (the deposit, though in the highlands, is itself only lightly to moderately cratered). This should enable access to in situ stratigraphy. The actual landing site will be selected where slopes are not expected to be steep, such that the rover itself should be able to traverse them and sample layered materials on the way, either up or down the slope. Perhaps due to uncertainties at this time as to the friability or meter-scale roughness of the deposit, it might make sense to place the landing ellipse on the exhumed highland surface adjacent to the deflated margin of the deposit and plan on driving to the deposit rather than landing on it and driving downslope. This should also enable imaging the margin for evidence of layering should it prove too difficult to climb. A target ellipse on the highland surface should also allow Athena access to ancient Noachian highland materials, particularly if placed near crater ejecta or an inlier of knobby material. Secondary Landing Site: Southern Elysium Planitia (Proposed by T. J. Parker) Vital Statistics: (1) Latitude, Longitude: 1.5-3.5 S, 195-198 W. (2) Elevation (Viking): -1.0 km. (3) Viking Orbiter Image coverage: Excellent coverage by 15 - 25 m/pixel images (orbit 725). Possible stereo coverage between images from beginning and end of orbit that overlap (probably small parallax angle) (4) Albedo: about .27-.28 (5) Block Abundance: 4-7% (6) Fine-Component Thermal Inertia: about 3 cgs units This region consists of eroded knobby material, probably of Noachian age, though much of the crater population has been destroyed, that is onlapped at a sharp contact by an extensive plains unit in southern Elysium Planitia that is Amazonian in age. The plains materials have been attributed to unusually low-viscosity flood lavas from fissures south of the Elysium volcanic rise, or to lacustrine materials associated with a large, Amazonian lake at the source of Marte Vallis. Parker and Schenk presented evidence in support of the latter interpretation, though they attributed the putative shore morphology to an embayment of a northern plains ocean into the southern Elysium region. Detailed examination of the margin of the deposit, showing erosion, not simply burial, of small crater rims and fluidized ejecta blankets, also points to lacustrine or marine sedimentation rather than volcanic plains burial. The plains surface exhibits a "crusty" appearance that many researchers have attributed to pressure ridges in lava flows. In a lacustrine context, they also resemble pressure ridges in desiccated evaporite deposits and salt-rimmed pools (now dry) similar in scale and morphology to spectacular, hundred meter-scale pool rims in alkaline Lake Natron, East African Rift. The eroded highland margin surface adjacent to these plains appears to be fairly smooth, even at 15 m/pixel. Isolated knob inliers are scattered from a few kilometers to several tens of "kilometers apart. Heights of the knobs have not been measured yet but, based on experience with similar features in the Pathfinder landing ellipse, are probably typically on the order of several tens of meters high and smaller, though some of the largest knobs in the region are probably up to a few hundred meters high. Two craters larger than a kilometer in diameter, with fluidized deposits, lie nearby the proposed landing site. Very high-resolution images from MOC should help to determine whether a landing site navigable by the Athena rover could be placed in this region. The space between knobs and craters is large enough to enable placement of a target landing ellipse between them but still provide access to one or more of them and to the margin of the Elysium plains material. Post -2001 Mars Surveyor Landing Site: Argyre Planitia (Proposed by T. J. Parker) Vital Statistics: (1) Latitude, Longitude: 55-56 S, 41-43 W. (2) Elevation (Viking): 1.0 km. (3) Viking Orbiter Image coverage: Excellent coverage by 40 m/pixel images (orbits 567B, 568B, and 569B). Excellent stereo coverage with large parallax angles over the entire landing site region, and much of central and southern Argyre. (4) Albedo: about .23-.24 (5) Block Abundance: No data (6) Fine-Component Thermal Inertia: No data The floors of both the Argyre and Hellas basins contain etched layered materials that are probably thick accumulations of channel or lacustrine sediments. The deposits in Hellas are much more eroded than those in Argyre, and Hellas lacks a channel outlet. Argyre is unique in that Uzboi Vallis flowed out of the basin, requiring overflow of a standing body of water within Argyre. This makes it the largest impact basin on Mars with channels both draining into it and flowing out from it. Hellas' channels may be catastrophic flood channels, whereas Argyre was fed by modest-scale valley networks, though the outlet at Uzboi Vallis was a catastrophic flood Highland craters and basins of this kind should be high-priority landing targets for missions intended to focus on the search for either prebiotic organic materials or even simple fossil microorganisms. Basins with internally-draining valley networks should be preferred over flood channels, as they could have provided the long-term influx of water favorable to the origin of life. (Catastrophic floods are not conducive to fossil preservation, due to their very short durations and high transportation energies). They also afford an opportunity to study the evolution of the planet's climate and volatiles during the period of time between the late Noachian and early Hesperian, when a drastic change from a proposed early warm, wet climate to one more closely resembling the modern environment is thought to have occurred. Large basin

Hydro-meteorological risk reduction and climate change adaptation in the Sava River Basin

NASA Astrophysics Data System (ADS)

Brilly, Mitja; Šraj, Mojca; Kryžanowski, Andrej

2017-04-01

The Sava River Basin covered the teritory of several countries. There were, in past thirty years, several flood hazard events with almost hundred years return period. Parts of the basin suffer by severe droughts also. In the presentation we covered questions of: • Flood hazard in complex hydrology structure • Landslide and flush flood in mountainous regions • Floods on karst polje • Flood risk management in the complex international and hydrological condition. • Impact of man made structures: hydropower storages, inundation ponds, river regulation, alternate streams, levees system, pumping stations, Natura 2000 areas etc. • How to manage droughts in the international river basin The basin is well covered by information and managed by international the SRB Commission (http://savacommission.org/) that could help. We develop study for climate change impact on floods on entire river basin financing by UNECE. There is also study provide climate change impact on the water management provide by World Bank and on which we take part. Recently is out call by world bank for study »Flood risk management plan for the SRB«.

Applying simple water-energy balance frameworks to predict the climate sensitivity of streamflow over the continental United States

NASA Astrophysics Data System (ADS)

Renner, M.; Bernhofer, C.

2012-08-01

The prediction of climate effects on terrestrial ecosystems and water resources is one of the major research questions in hydrology. Conceptual water-energy balance models can be used to gain a first order estimate of how long-term average streamflow is changing with a change in water and energy supply. A common framework for investigation of this question is based on the Budyko hypothesis, which links hydrological response to aridity. Recently, Renner et al. (2012) introduced the climate change impact hypothesis (CCUW), which is based on the assumption that the total efficiency of the catchment ecosystem to use the available water and energy for actual evapotranspiration remains constant even under climate changes. Here, we confront the climate sensitivity approaches (the Budyko approach of Roderick and Farquhar, 2011, and the CCUW) with data of more than 400 basins distributed over the continental United States. We first estimate the sensitivity of streamflow to changes in precipitation using long-term average data of the period 1949 to 2003. This provides a hydro-climatic status of the respective basins as well as their expected proportional effect to changes in climate. Next, we test the ability of both approaches to predict climate impacts on streamflow by splitting the data into two periods. We (i) analyse the long-term average changes in hydro-climatology and (ii) derive a statistical classification of potential climate and basin change impacts based on the significance of observed changes in runoff, precipitation and potential evapotranspiration. Then we (iii) use the different climate sensitivity methods to predict the change in streamflow given the observed changes in water and energy supply and (iv) evaluate the predictions by (v) using the statistical classification scheme and (vi) a conceptual approach to separate the impacts of changes in climate from basin characteristics change on streamflow. This allows us to evaluate the observed changes in streamflow as well as to assess the impact of basin changes on the validity of climate sensitivity approaches. The apparent increase of streamflow of the majority of basins in the US is dominated by an increase in precipitation. It is further evident that impacts of changes in basin characteristics appear simultaneously with climate changes. There are coherent spatial patterns with catchments where basin changes compensate for climatic changes being dominant in the western and central parts of the US. A hot spot of basin changes leading to excessive runoff is found within the US Midwest. The impact of basin changes on the prediction is large and can be twice as much as the observed change signal. Although the CCUW and the Budyko approach yield similar predictions for most basins, the data of water-limited basins support the Budyko framework rather than the CCUW approach, which is known to be invalid under limiting climatic conditions.

Depth and Differentiation of the Orientale Melt Lake

NASA Technical Reports Server (NTRS)

Vaughan, W. M.; Head, J. W.; Hess, P. C.; Wilson, L.; Neumann, G. A.; Smith, D. E.; Zuber, M. T.

2012-01-01

Impact melt emplacement and evolution in lunar multi-ring basins is poorly understood since impact melt deposits in basins are generally buried by mare basalt fill and obscured by subsequent impact cratering. The relatively young Orientale basin, which is only partially flooded with mare basalt, opens a rare window into basin-scale impact melts. We describe the geology of impact melt-related facies in Orientale and suggest that the central depression of Orientale may represent a solidified impact melt lake that vertically subsided shortly after basin formation due to solidification and cooling. We use Lunar Orbiter Laser Altimeter (LOLA) data to measure the depth (approx. 1.75 km) and diameter (approx 350 km) of this central depression. If all the observed subsidence of the central depression is due to solidification and cooling, the melt lake should be approx 12.5-16 km deep, far more voluminous (approx 106 km3) than the largest known differentiated igneous intrusions on Earth. We investigate the possibility that the Orientale melt lake has differentiated and model 1) the bulk composition of the melt lake, 2) the operation of melt mixing in the melt lake, and 3) the chemical evolution of the resulting liquids on the An-Fo-Qz ternary in order to predict the lithologies that might be present in the solidified Orientale melt lake. Finally, we consider the possible significance of these lithologies.

Magnetic anomalies in the Imbrium and Schrödinger impact basins: Orbital evidence for persistence of the lunar core dynamo into the Imbrian epoch

NASA Astrophysics Data System (ADS)

Hood, L. L.; Spudis, P. D.

2016-11-01

Approximate maps of the lunar crustal magnetic field at low altitudes in the vicinities of the three Imbrian-aged impact basins, Orientale, Schrödinger, and Imbrium, have been constructed using Lunar Prospector and Kaguya orbital magnetometer data. Detectable anomalies are confirmed to be present well within the rims of Imbrium and Schrödinger. Anomalies in Schrödinger are asymmetrically distributed about the basin center, while a single isolated anomaly is most clearly detected within Imbrium northwest of Timocharis crater. The subsurface within these basins was heated to high temperatures at the time of impact and required long time periods (up to 1 Myr) to cool below the Curie temperature for metallic iron remanence carriers (1043 K). Therefore, consistent with laboratory analyses of returned samples, a steady, long-lived magnetizing field, i.e., a former core dynamo, is inferred to have existed when these basins formed. The asymmetrical distribution within Schrödinger suggests partial demagnetization by later volcanic activity when the dynamo field was much weaker or nonexistent. However, it remains true that anomalies within Imbrian-aged basins are much weaker than those within most Nectarian-aged basins. The virtual absence of anomalies within Orientale where impact melt rocks (the Maunder Formation) are exposed at the surface is difficult to explain unless the dynamo field was much weaker during the Imbrian period.

Overview of ecotoxicological studies performed in the Venice Lagoon (Italy).

PubMed

Losso, C; Ghirardini, A Volpi

2010-01-01

This work reports on the state of the art of the bioindicators used to assess environmental quality (regarding chemical pollutant impacts) in the Venice lagoon. After a brief description of the roles, advantages and limitations of bioindicators in marine and transitional environments and a summary of the Venice lagoon characteristics, the ecotoxicological methods used during scientific studies and research projects in the Lagoon are reported. Since not all data are available and no database can be formulated, the main evidence from toxicity bioassays, biomarkers and bioaccumulation analyses since the end of the 1970s is spatially synthesized using maps and discussed according to the four Venice lagoon basins. The majority of indicators showed that the Lido basin (north-central lagoon), affected by the presence of the industrial area and the city of Venice, is the one most highly impacted (particularly in the sites located within or in front of the industrial area, which showed very high sediment toxicity and high levels of DNA damage). The Malamocco basin (south-central lagoon) seems to be the least problematic. The southern basin (Chioggia basin) was shown to be impacted by urban contaminants from the town of Chioggia. The northern basin (Treporti basin) presented both impacted sites (high toxicity and high bioaccumulation factor) and relatively unpolluted sites (absence of toxicity, absence of imposex and low levels of bioaccumulation). This review can serve as a basis on which to select pragmatic, cost-effective biomonitoring techniques for environmental effects in lagoon ecosystems.

Noachian and Hesperian modification of the original Chryse impact basin topography

NASA Technical Reports Server (NTRS)

Stockman, S. A.; Frey, H.

1995-01-01

We prospose a new center and ring assignment for the original Chryse impact basin based upon photogeologic mapping of Noachian outcrops and re-examination of the published geology using orthographic projections. While others have centered the Chryse impact on the topographic low associated with Hesperian volcanic and fluvial deposits, we suggest that the center of the Noachian-age excavation cavity was located approximately 800 km to the north, and that the basin topography was modified significantly from the Noachian into the Hesperian. Evolution of the topographic low included structural modification by a later impact centered in Acidalia, restricted volcanic deposition and loading, localized subsidence, and restricted deposition from the circum-Chryse outlfow channels.

Examining Topography of Mars Impact Basins to Determine If Impact Basins Have Topographic Characteristics of a Crater

NASA Technical Reports Server (NTRS)

Livingston, A.; Lewis, K.; Simmons, J.; Chavez, D.; Gchachu, K.; Newsom, H. E.; Sutherland, V.; Gordon, H.; Hare, T. M.

2003-01-01

Determining the topography of suspect craters on Mars will help scientists better understand the land deformation that occurs from an asteroid or comet impact. This will provide a better understanding of how Mars has changed over time and the topography data could be used for planning future missions to Mars. We have begun a program at the Southwestern Indian Polytechnic Institute (SIPI), a Bureau of Indian Affairs junior college, to analyze large impact basins on Mars (>300 km diameter) utilizing Geographic Information System (GIS) technology. Collaborators at the University of New Mexico and the U.S. Geological Survey are providing technical support for this effort.

Formation of the Sputnik Planum basin and the thickness of Pluto's subsurface ocean

NASA Astrophysics Data System (ADS)

Johnson, Brandon C.; Bowling, Timothy J.; Trowbridge, Alexander J.; Freed, Andrew M.

2016-10-01

We simulate the formation of the large elliptical impact basin associated with Pluto's Sputnik Planum (SP; informal name). The location of SP suggests that it represents a large positive mass anomaly. To find the conditions necessary for SP to have a positive mass anomaly, we consider impacts into targets with a range of thermal states and ocean thicknesses. Assuming the basin evolves to its current-day configuration, we calculate the mass and gravity anomalies associated with SP. We find that SP can only achieve a large positive mass anomaly if Pluto has a more than 100 km thick salty ocean. This conclusion may help us better understand the composition and thermal evolution of Pluto. Furthermore, our work supports the hypothesis that SP basin has an impact origin.

Controls and variability of solute and sedimentary fluxes in Arctic and sub-Arctic Environments

NASA Astrophysics Data System (ADS)

Dixon, John

2015-04-01

Six major factors consistently emerge as controls on the spatial and temporal variability in sediment and solute fluxes in cold climates. They are climatic, geologic, physiographic or relief, biologic, hydrologic, and regolith factors. The impact of these factors on sediment and solute mass transfer in Arctic and sub-Arctic environments is examined. Comparison of non-glacierized Arctic vs. subarctic drainage basins reveals the effects of these controls. All drainage basins exhibit considerable variability in rates of sediment and solute fluxes. For the non-glacierized drainage basins there is a consistent increase in sediment mass transfer by slope processes and fluvial processes as relief increases. Similarly, a consistent increase in sediment mass transfer by slope and fluvial processes is observed as total precipitation increases. Similar patterns are also observed with respect to solute transport and relief and precipitation. Lithologic factors are most strongly observed in the contrast between volcanic vs. plutonic igneous bedrock substrates. Basins underlain by volcanic rocks display greater mass transfers than those underlain by plutonic rocks. Biologic influences are most strongly expressed by variations in extent of vegetation cover and the degree of human interference, with human impacted basins generating greater fluxes. For glacierized basins the fundamental difference to non-glacierized basins is an overall increase in mean annual mass transfers of sediment and a generally smaller magnitude solute transfer. The principal role of geology is observed with respect to lithology. Catchments underlain by limestone demonstrate substantially greater solute mass transfers than sediment transfer. The influence of relief is seen in the contrast in mass transfers between upland and lowland drainage basins with upland basins generating greater sediment and solute transfers than lowland basins. For glacierized basins the effects of biology and regolith appear to be largely overridden by the hydrologic impacts of glacierization.

HUBBLE TRACKS 'PERFECT STORM' ON MARS

NASA Technical Reports Server (NTRS)

2002-01-01

Two dramatically different faces of our Red Planet neighbor appear in these comparison images showing how a global dust storm engulfed Mars with the onset of Martian spring in the Southern Hemisphere. When NASA's Hubble Space Telescope imaged Mars in June, the seeds of the storm were caught brewing in the giant Hellas Basin (oval at 4 o'clock position on disk) and in another storm at the northern polar cap. When Hubble photographed Mars in early September, the storm had already been raging across the planet for nearly two months obscuring all surface features. The fine airborne dust blocks a significant amount of sunlight from reaching the Martian surface. Because the airborne dust is absorbing this sunlight, it heats the upper atmosphere. Seasonal global Mars dust storms have been observed from telescopes for over a century, but this is the biggest storm ever seen in the past several decades. Mars looks gibbous in the right photograph because it is 26 million miles farther from Earth than in the left photo (though the pictures have been scaled to the same angular size), and our viewing angle has changed. The left picture was taken when Mars was near its closest approach to Earth for 2001 (an event called opposition); at that point the disk of Mars was fully illuminated as seen from Earth because Mars was exactly opposite the Sun. Both images are in natural color, taken with Hubble's Wide Field Planetary Camera 2. Credit: NASA, James Bell (Cornell Univ.), Michael Wolff (Space Science Inst.), and the Hubble Heritage Team (STScI/AURA)

Spectral Anomalies in the 11 and 12 micron Region From the Mariner Mars 7 Infrared Spectrometer

NASA Technical Reports Server (NTRS)

Kirkland, Laurel E.; Herr, Kenneth C.

2000-01-01

Two hundred-forty infrared spectra acquired by the 1969 Mariner Mars 7 Infrared Spectrometer (IRS), spanning the wavelength region 1.8-14.4 micron (5550-690/cm), have recently been recovered and calibrated in both wavelength and intensity. An examination of these IRS spectra has revealed absorptions at 11.25 and 12.5 micron that have not previously been reported for Mars. A search of the literature and spectral data bases shows that materials that exhibit a doublet at 11.25 and 12.5 micron are rare. In this paper we examine potential causes for these features and include a detailed discussion of carbonates, goethite, CO2 ice, and water ice. CO2 ice and water ice measured in transmission do not exhibit bands that match those recorded at 11.25 and 12.5 micron for Mars, which indicates that CO2 or water ice clouds are not the source of these features. Since these bands show no clear correlation with atmospheric path length, they are most likely caused by a surface material. In the IRS database they appear to be exceptionally intense in the western part of the Hellas basin. Goethite exhibits bands that are a good spectral match, but confirming whether goethite causes the features will require additional studies of the 20-50 micron region. These studies will require laboratory measurements of weathering coatings and an examination of spectra recorded of Mars by the 1971 Mariner Mars Infrared Interferometer Spectrometer (IRIS; 5-50 micron 2000200/cm) and the 1996 Thermal Emission Spectrometer (TES; 6-50 micron 1667-200/cm).

Basin-wide Assessment of Climate Change Impacts on Ecosystems and Biodiversity

EPA Science Inventory

Mekong ecosystems are under pressure from a number of "drivers", including rapid economic development, population growth, unsustainable resource use, and climate change. Ecological modeling can help assess vulnerability and impacts of these drivers on the Lower Mekong Basin.

Impacts of Oil Shale Development on Education in the Uintah Basin. A Report on a Community Based Approach to Education Planning in Communities Facing Rapid Growth.

ERIC Educational Resources Information Center

Lindberg, Denise P.

Three counties in eastern Utah's Uintah Basin face the likelihood of rapid growth because of planned oil shale and tar sands development in the area. This seven-part report describes a federally-funded, community-based project to plan for expected impacts of the energy developments on Uintah Basin education. After an introductory overview, the…

Results of measurements with the Planetary Fourier Spectrometer onboard Mars Express: Clouds and dust at the end of southern summer. A comparison with OMEGA images

NASA Astrophysics Data System (ADS)

Zasova, L. V.; Formisano, V.; Moroz, V. I.; Bibring, J.-P.; Grassi, D.; Ignatiev, N. I.; Giuranna, M.; Bellucci, G.; Altieri, F.; Blecka, M.; Gnedykh, V. N.; Grigoriev, A. V.; Lellouch, E.; Mattana, A.; Maturilli, A.; Moshkin, B. E.; Nikolsky, Yu. V.; Patsaev, D. V.; Piccioni, G.; Ratai, M.; Saggin, B.; Fonti, S.; Khatuntsev, I. V.; Hirsh, H.; Ekonomov, A. P.

2006-07-01

We discuss the results of measurements made with the Planetary Fourier Spectrometer (PFS) onboard the Mars Express spacecraft. The data were obtained in the beginning of the mission and correspond to the end of summer in the southern hemisphere of Mars ( L s ˜ 340°). Three orbits are considered, two of which passed through volcanoes Olympus and Ascraeus Mons (the height above the surface is about +20 km), while the third orbit intersects lowland Hellas (-7 km). The influence of the relief on the properties of the aerosol observed is demonstrated: clouds of water ice with a visual optical thickness of 0.1-0.5 were observed above volcanoes, while only dust was found during the observations (close in time) along the orbit passing through Hellas in low and middle latitudes. This dust is homogeneously mixed with gas and has a reduced optical thickness of 0.25±0.05 (at v = 1100 cm-1). In addition to orographic clouds, ice clouds were observed in this season in the northern polar region. The clouds seen in the images obtained simultaneously by the mapping spectrometer OMEGA confirm the PFS results. Temperature inversion is discovered in the north polar hood below the level 1 mbar with a temperature maximum at about 0.6 mbar. This inversion is associated with descending movements in the Hadley cell.

Ambient concentrations of total suspended particulate matter and its elemental constituents at the wider area of the mining facilities of TVX Hellas in Chalkidiki, Greece.

PubMed

Gaidajis, George

2003-01-01

To assess ambient air quality at the wider area of TVX Hellas mining facilities, the Total Suspended Particulate matter (TSP) and its content in characteristic elements, i.e., As, Cd, Cu, Fe, Mn, Pb, Zn are being monitored for more than thirty months as part of the established Environmental Monitoring Program. High Volume air samplers equipped with Tissue Quartz filters were employed for the collection of TSP. Analyses were effected after digestion of the suspended particulate with an HNO3-HCl solution and determination of elemental concentrations with an Atomic Absorption Spectroscopy equipped with graphite furnace. The sampling stations were selected to record representatively the existing ambient air quality in the vicinity of the facilities and at remote sites not affected from industrial activities. Monitoring data indicated that the background TSP concentrations ranged from 5-60 microg/m3. Recorded TSP concentrations at the residential sites close to the facilities ranged between 20-100 microg/m3, indicating only a minimal influence from the mining and milling activities. Similar spatial variation was observed for the TSP constituents and specifically for Pb and Zn. To validate the monitoring procedures, a parallel sampling campaign took place with different High Volume samplers at days where low TSP concentrations were expected. The satisfactory agreement (+/- 11%) at low concentrations (50-100 microg/m3) clearly supported the reproducibility of the techniques employed specifically at the critical range of lower concentrations.

Magnetic Fields of Lunar Impact Basins and Their Use in Constraining the Impact Process

NASA Astrophysics Data System (ADS)

Halekas, J. S.; Lin, R. P.

2003-01-01

Measurements by the Magnetometer/Electron Reflectometer instrument on the Lunar Prospector spacecraft, which completed its mapping mission in 1999, have been used to construct the first completely global maps of lunar crustal magnetic fields. Now, for the first time, we have a data set with global coverage and a sensitivity and resolution which allow us to investigate the magnetic fields of lunar impact basins and craters. As on the Earth, impact sites have a variety of magnetic signatures associated with them, ranging from nearly complete demagnetization to strong central magnetic anomalies. Observations of the magnetic fields of terrestrial basins have been used to make inferences about the impact process, and we wish to show that lunar observations can also provide valuable constraints.

Could giant basin-forming impacts have killed Martian dynamo?

PubMed Central

Kuang, W; Jiang, W; Roberts, J; Frey, H V

2014-01-01

The observed strong remanent crustal magnetization at the surface of Mars suggests an active dynamo in the past and ceased to exist around early to middle Noachian era, estimated by examining remagnetization strengths in extant and buried impact basins. We investigate whether the Martian dynamo could have been killed by these large basin-forming impacts, via numerical simulation of subcritical dynamos with impact-induced thermal heterogeneity across the core-mantle boundary. We find that subcritical dynamos are prone to the impacts centered on locations within 30° of the equator but can easily survive those at higher latitudes. Our results further suggest that magnetic timing places a strong constraint on postimpact polar reorientation, e.g., a minimum 16° polar reorientation is needed if Utopia is the dynamo killer. PMID:26074641

Could Giant Basin-Forming Impacts Have Killed Martian Dynamo?

NASA Technical Reports Server (NTRS)

Kuang, W.; Jiang, W.; Roberts, J.; Frey, H. V.

2014-01-01

The observed strong remanent crustal magnetization at the surface of Mars suggests an active dynamo in the past and ceased to exist around early to middle Noachian era, estimated by examining remagnetization strengths in extant and buried impact basins. We investigate whether the Martian dynamo could have been killed by these large basin-forming impacts, via numerical simulation of subcritical dynamos with impact-induced thermal heterogeneity across the core-mantle boundary. We find that subcritical dynamos are prone to the impacts centered on locations within 30 deg of the equator but can easily survive those at higher latitudes. Our results further suggest that magnetic timing places a strong constraint on postimpact polar reorientation, e.g., a minimum 16 deg polar reorientation is needed if Utopia is the dynamo killer.

Could giant basin-forming impacts have killed Martian dynamo?

PubMed

Kuang, W; Jiang, W; Roberts, J; Frey, H V

2014-11-28

The observed strong remanent crustal magnetization at the surface of Mars suggests an active dynamo in the past and ceased to exist around early to middle Noachian era, estimated by examining remagnetization strengths in extant and buried impact basins. We investigate whether the Martian dynamo could have been killed by these large basin-forming impacts, via numerical simulation of subcritical dynamos with impact-induced thermal heterogeneity across the core-mantle boundary. We find that subcritical dynamos are prone to the impacts centered on locations within 30° of the equator but can easily survive those at higher latitudes. Our results further suggest that magnetic timing places a strong constraint on postimpact polar reorientation, e.g., a minimum 16° polar reorientation is needed if Utopia is the dynamo killer.

Impacts of golden alga Prymnesium parvum on fish populations in reservoirs of the upper Colorado River and Brazos River basins, Texas

USGS Publications Warehouse

VanLandeghem, Matthew M.; Farooqi, Mukhtar; Farquhar, B.; Patino, Reynaldo

2013-01-01

Several reservoirs in the upper Colorado River and Brazos River basins in Texas have experienced toxic blooms of golden alga Prymnesium parvum and associated fish kills since 2001. There is a paucity of information, however, regarding the population-level effects of such kills in large reservoirs, species-specific resistance to or recovery from kills, or potential differences in the patterns of impacts among basins. We used multiple before-after, control-impact analysis to determine whether repeated golden alga blooms have led to declines in the relative abundance and size structure of fish populations. Sustained declines were noted for 9 of 12 fish species surveyed in the upper Colorado River, whereas only one of eight species was impacted by golden alga in the Brazos River. In the upper Colorado River, White Bass Morone chrysops, White Crappie Pomoxis annularis, Largemouth Bass Micropterus salmoides, Bluegill Lepomis macrochirus, River Carpsucker Carpiodes carpio, Freshwater Drum Aplodinotus grunniens, Channel Catfish Ictalurus punctatus, Flathead Catfish Pylodictis olivaris, and Blue Catfish I. furcatus exhibited sustained declines in relative abundance, size structure, or both; Gizzard Shad Dorosoma cepedianum, Longnose Gar Lepisosteus osseus, and Common Carp Cyprinus carpio did not exhibit those declines. In the Brazos River, only the relative abundance of Blue Catfish was impacted. Overall, toxic golden alga blooms can negatively impact fish populations over the long-term, but the patterns of impact can vary considerably among river basins and species. In the Brazos River, populations of most fish species appear to be healthy, suggesting a positive angling outlook for this basin. In the upper Colorado River, fish populations have been severely impacted, and angling opportunities have been reduced. Basin-specific management plans aimed at improving water quality and quantity will likely reduce bloom intensity and allow recovery of fish populations to the abundances and size structures present before golden alga. Received August 26, 2011; accepted November 25, 2012

Statistical analysis of the magnetization signatures of impact basins

NASA Astrophysics Data System (ADS)

Gabasova, L. R.; Wieczorek, M. A.

2017-09-01

We quantify the magnetic signatures of the largest lunar impact basins using recent mission data and robust statistical bounds, and obtain an early activity timeline for the lunar core dynamo which appears to peak earlier than indicated by Apollo paleointensity measurements.

Basin-ring spacing on the Moon, Mercury, and Mars

USGS Publications Warehouse

Pike, R.J.; Spudis, P.D.

1987-01-01

Radial spacing between concentric rings of impact basins that lack central peaks is statistically similar and nonrandom on the Moon, Mercury, and Mars, both inside and outside the main ring. One spacing interval, (2.0 ?? 0.3)0.5D, or an integer multiple of it, dominates most basin rings. Three analytical approaches yield similar results from 296 remapped or newly mapped rings of 67 multi-ringed basins: least-squares of rank-grouped rings, least-squares of rank and ring diameter for each basin, and averaged ratios of adjacent rings. Analysis of 106 rings of 53 two-ring basins by the first and third methods yields an integer multiple (2 ??) of 2.00.5D. There are two exceptions: (1) Rings adjacent to the main ring of multi-ring basins are consistently spaced at a slightly, but significantly, larger interval, (2.1 ?? 0.3)0.5D; (2) The 88 rings of 44 protobasins (large peak-plus-inner-ring craters) are spaced at an entirely different interval (3.3 ?? 0.6)0.5D. The statistically constant and target-invariant spacing of so many rings suggests that this characteristic may constrain formational models of impact basins on the terrestrial planets. The key elements of such a constraint include: (1) ring positions may not have been located by the same process(es) that formed ring topography; (2) ring location and emplacement of ring topography need not be coeval; (3) ring location, but not necessarily the mode of ring emplacement, reflects one process that operated at the time of impact; and (4) the process yields similarly-disposed topographic features that are spatially discrete at 20.5D intervals, or some multiple, rather than continuous. These four elements suggest that some type of wave mechanism dominates the location, but not necessarily the formation, of basin rings. The waves may be standing, rather than travelling. The ring topography itself may be emplaced at impact by this and/or other mechanisms and may reflect additional, including post-impact, influences. ?? 1987 D. Reidel Publishing Company.

Hydrological Impacts of Land Use Change and Climate Variability in the Headwater Region of the Heihe River Basin, Northwest China

PubMed Central

Zhang, Ling; Nan, Zhuotong; Xu, Yi; Li, Shuo

2016-01-01

Land use change and climate variability are two key factors impacting watershed hydrology, which is strongly related to the availability of water resources and the sustainability of local ecosystems. This study assessed separate and combined hydrological impacts of land use change and climate variability in the headwater region of a typical arid inland river basin, known as the Heihe River Basin, northwest China, in the recent past (1995–2014) and near future (2015–2024), by combining two land use models (i.e., Markov chain model and Dyna-CLUE) with a hydrological model (i.e., SWAT). The potential impacts in the near future were explored using projected land use patterns and hypothetical climate scenarios established on the basis of analyzing long-term climatic observations. Land use changes in the recent past are dominated by the expansion of grassland and a decrease in farmland; meanwhile the climate develops with a wetting and warming trend. Land use changes in this period induce slight reductions in surface runoff, groundwater discharge and streamflow whereas climate changes produce pronounced increases in them. The joint hydrological impacts are similar to those solely induced by climate changes. Spatially, both the effects of land use change and climate variability vary with the sub-basin. The influences of land use changes are more identifiable in some sub-basins, compared with the basin-wide impacts. In the near future, climate changes tend to affect the hydrological regimes much more prominently than land use changes, leading to significant increases in all hydrological components. Nevertheless, the role of land use change should not be overlooked, especially if the climate becomes drier in the future, as in this case it may magnify the hydrological responses. PMID:27348224

Hydrological Impacts of Land Use Change and Climate Variability in the Headwater Region of the Heihe River Basin, Northwest China.

PubMed

Zhang, Ling; Nan, Zhuotong; Xu, Yi; Li, Shuo

2016-01-01

Land use change and climate variability are two key factors impacting watershed hydrology, which is strongly related to the availability of water resources and the sustainability of local ecosystems. This study assessed separate and combined hydrological impacts of land use change and climate variability in the headwater region of a typical arid inland river basin, known as the Heihe River Basin, northwest China, in the recent past (1995-2014) and near future (2015-2024), by combining two land use models (i.e., Markov chain model and Dyna-CLUE) with a hydrological model (i.e., SWAT). The potential impacts in the near future were explored using projected land use patterns and hypothetical climate scenarios established on the basis of analyzing long-term climatic observations. Land use changes in the recent past are dominated by the expansion of grassland and a decrease in farmland; meanwhile the climate develops with a wetting and warming trend. Land use changes in this period induce slight reductions in surface runoff, groundwater discharge and streamflow whereas climate changes produce pronounced increases in them. The joint hydrological impacts are similar to those solely induced by climate changes. Spatially, both the effects of land use change and climate variability vary with the sub-basin. The influences of land use changes are more identifiable in some sub-basins, compared with the basin-wide impacts. In the near future, climate changes tend to affect the hydrological regimes much more prominently than land use changes, leading to significant increases in all hydrological components. Nevertheless, the role of land use change should not be overlooked, especially if the climate becomes drier in the future, as in this case it may magnify the hydrological responses.

Mega-Impacts on Mars: Implications for the Late Heavy Bombardment in the Inner Solar System, and the Early Evolution of the Earth and Mars

NASA Technical Reports Server (NTRS)

Frey, Herbert

2012-01-01

There are about 30 very large impact basins on Mars, > 1000 km in diameter, most of which are revealed by their topographic and/or crustal thickness signatures. Crater retention ages and model absolute ages suggest these all formed in a relatively short time (100-200 million years?), perhaps during a "Late Heavy Bombardment" (LHB) caused by the evolution of the orbits of the giant planets. This so-called "Nice Model" of planetary formation may explain the LHB on the Moon at about 3.9 billion years ago and would have produced a similar bombardment throughout the inner solar system. The formation of 30 very large impact basins would have had catastrophic environmental consequences for Mars, which were further complicated by the demise of the global magnetic field at about the same time. If there are no very large basins on Mars older than the 30 we see and the LHB really lasted everywhere only a short time, there may have been a relatively longer time (400 million years?) during which Mars and the Earth suffered no major impact trauma and during which conditions on both worlds may have been far more habitable than during the LHB. However, if the formation of the Mars crustal dichotomy was due to an even larger giant impact that predated the very large basins, all record of this earlier and possibly more clement time on Mars may have been erased. Ages of the smaller but still very large basins can be used to approximately date the giant impact (if it occurred). Even the very large basins appear to have reset the crater retention ages of the entire crust of Mars and may have by themselves erased any record of an earlier time.

An impact-driven dynamo for the early Moon.

PubMed

Le Bars, M; Wieczorek, M A; Karatekin, O; Cébron, D; Laneuville, M

2011-11-09

The origin of lunar magnetic anomalies remains unresolved after their discovery more than four decades ago. A commonly invoked hypothesis is that the Moon might once have possessed a thermally driven core dynamo, but this theory is problematical given the small size of the core and the required surface magnetic field strengths. An alternative hypothesis is that impact events might have amplified ambient fields near the antipodes of the largest basins, but many magnetic anomalies exist that are not associated with basin antipodes. Here we propose a new model for magnetic field generation, in which dynamo action comes from impact-induced changes in the Moon's rotation rate. Basin-forming impact events are energetic enough to have unlocked the Moon from synchronous rotation, and we demonstrate that the subsequent large-scale fluid flows in the core, excited by the tidal distortion of the core-mantle boundary, could have powered a lunar dynamo. Predicted surface magnetic field strengths are on the order of several microteslas, consistent with palaeomagnetic measurements, and the duration of these fields is sufficient to explain the central magnetic anomalies associated with several large impact basins.

Ringed impact craters on Venus: An analysis from Magellan images

NASA Technical Reports Server (NTRS)

Alexopoulos, Jim S.; Mckinnon, William B.

1992-01-01

We have analyzed cycle 1 Magellan images covering approximately 90 percent of the venusian surface and have identified 55 unequivocal peak-ring craters and multiringed impact basins. This comprehensive study (52 peak-ring craters and at least 3 multiringed impact basins) complements our earlier independent analysis of Arecibo and Venera images and initial Magellan data and that of the Magellan team.

FUTURE WATER ALLOCATION AND IN-STREAM VALUES IN THE WILLAMETTE RIVER BASIN: A BASIN-WIDE ANALYSIS

EPA Science Inventory

Our research investigated the impact on surface water resources of three different scenarios for the future development of the Willamette River Basin in Oregon (USA). Water rights in the basin, and in the western United States in general, are based on a system of law that binds ...

76 FR 75876 - Record of Decision for the Modification of the Groton Generation Station Interconnection...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-12-05

...) received a request from Basin Electric Power Cooperative (Basin Electric) to modify its Large Generator Interconnection Agreement (LGIA) with Basin Electric for the Groton Generation Station to eliminate current... considered the environmental impacts and has decided to modify its LGIA with Basin Electric for the Groton...

Vulnerability of supply basins to demand from multiple cities

NASA Astrophysics Data System (ADS)

Padowski, J. C.; Gorelick, S.

2013-12-01

Humans have appropriated more than half of the world's available water resources, and continued population growth and climate change threaten to put increasing pressure on remaining supplies. Many cities have constructed infrastructure to collect, transport from and store water at distant locations. Supply basins can become vulnerable if there are multiple users depending on the same supply system or network. Basin vulnerability assessments often only report the impacts of local demands on system health, but rarely account future stress from multi-urban demands. This study presents a global assessment of urban impacts on supply basins. Specifically, hydrologic and regulatory information are used to quantify the level of supply basin stress created by demand from multiple cities. The aim is to identify at-risk basins. This study focuses on large urban areas (generally over 1 million people) that use surface water (n=412). The stress on supply water basins by urban demand was based on three parameters: 1) the number of cities using a basin for water supply, 2) the number of alternative urban sources (e.g. lakes, reservoirs, rivers) within the supply basin, and 3) the percent of available surface water in each basin that is required to meet the total of urban and environmental demands. The degree of management within each basin is assessed using information on federal water policies and local basin management plans.

Multi-basin, Multi-sector Drought Economic Impact Model in Python: Development and Applications

NASA Astrophysics Data System (ADS)

Gutenson, J. L.; Zhu, L.; Ernest, A. N. S.; Oubeidillah, A.; Bearden, B.; Johnson, T. G.

2015-12-01

Drought is one of the most economically disastrous natural hazards, one whose impacts are exacerbated by the lack of abrupt onset and offset that define tornados and hurricanes. In the United States, about 30 billion dollars losses is caused by drought in 2012, resulting in widespread economic impacts for societies, industries, agriculture, and recreation. And in California, the drought cost statewide economic losses about 2.2 billion, with a total loss of 17,100 seasonal and part-time jobs. Driven by a variety of factors including climate change, population growth, increased water demands, alteration to land cover, drought occurs widely all over the world. Drought economic consequence assessment tool are greatly needed to allow decision makers and stakeholders to anticipate and manage effectively. In this study, current drought economic impact modeling methods were reviewed. Most of these models only deal with the impact in the agricultural sector with a focus on a single basin; few of these models analyze long term impact. However, drought impacts are rarely restricted to basin boundaries, and cascading economic impacts are likely to be significant. A holistic approach to multi-basin, multi-sector drought economic impact assessment is needed.In this work, we developed a new model for drought economic impact assessment, Drought Economic Impact Model in Python (PyDEM). This model classified all business establishments into thirteen categories based on NAICS, and using a continuous dynamic social accounting matrix approach, coupled with calculation of the indirect consequences for the local and regional economies and the various resilience. In addition, Environmental Policy Integrated Climate model was combined for analyzing drought caused soil erosion together with agriculture production, and then the long term impacts of drought were achieved. A visible output of this model was presented in GIS. In this presentation, Choctawhatchee-Pea-Yellow River Basins, Alabama was chosen as study area, and further application of PyDEM was discussed.

Morphologic studies of the Moon and planets

NASA Technical Reports Server (NTRS)

El-Baz, F.; Maxwell, T. A.

1984-01-01

The impact, volcanic, and tectonic history of the Moon and planets were investigated over an eight year period. Research on the following topics is discussed: lunar craters, lunar basins, lunar volcanoes, correlation of Apollo geochemical data, lunar geology, Mars desert landforms, and Mars impact basins.

Antipodal Magnetic Anomalies on the Moon, Contributions from Impact Induced Currents Due to Positive Holes and Flexoelectric Phenomina and Dynamo

NASA Technical Reports Server (NTRS)

Kletetschka, G.; Freund, F.; Wasilewski, P. J.; Mikula, V.; Kohout, Tomas

2005-01-01

Large impacts on the Moon generate large pressure pulses that penetrate the whole body. Several of these large impacts may have generated antipodal structure with anomalous magnetic intensity.These regions can be more than a thousand km across, with fields of the order of tens to hundreds of nT. This is the case of Orientale, Imbrium, Serenitatis, Crisium, and Nectaris impact basins. The production of large-scale magnetic fields and associated crustal magnetization due to lunar basin-forming impacts was hypothesized to have an origin in fields external to the impact plasma cloud that are produced by the magnetohydrodynamic interaction of the cloud with ambient magnetic fields and plasmas. During the period of compressed antipodal field amplification, seismic compressional waves from the impact converge at the antipode resulting in transient shock pressures that reach 2 GPa (20 kbar). This can produce conditions for shock magnetic acquisition of the crust antipodal to impact basins.

Land area changes in coastal Louisiana after Hurricanes Katrina and Rita: Chapter 5B in Science and the storms-the USGS response to the hurricanes of 2005

USGS Publications Warehouse

Barras, John A.

2007-01-01

Comparison of classified Landsat Thematic Mapper (TM) satellite imagery acquired before and after the landfalls of Hurricanes Katrina (August 29, 2005) and Rita (September 24, 2005) demonstrated that water area increased by 217 mi2 (562 km2) in coastal Louisiana. Approximately 82 mi2 (212 km2) of new water areas were in areas primarily impacted by Katrina (Mississippi River Delta basin, Breton Sound basin, Pontchartrain basin, Pearl River basin), whereas 117 mi2 (303 km2) were in areas primarily impacted by Rita (Calcasieu/ Sabine basin, Mermentau basin, Teche/Vermilion basin, Atchafalaya basin, Terrebonne basin). Barataria basin contained new water areas caused by both hurricanes, resulting in some 18 mi2 (46.6 km2) of new water areas. The fresh marsh and intermediate marsh communities' land areas decreased by 122 mi2 (316 km2) and 90 mi2 (233.1 km2), respectively. The brackish marsh and saline marsh communities' land areas decreased by 33 mi2 (85.5 km2) and 28 mi2 (72.5 km2), respectively. These new water areas identify permanent losses caused by direct removal of wetlands. They also indicate transitory water area changes caused by remnant flooding, removal of aquatic vegetation, scouring of marsh vegetation, and water-level variation attributed to normal tidal and meteorological variation between satellite images. Permanent losses cannot be estimated until several growing seasons have passed and the transitory impacts of the hurricanes are minimized. The purpose of this study was to provide preliminary information on water area changes in coastal Louisiana acquired shortly after both hurricanes' landfalls (detectable with Landsat TM imagery) and to serve as a regional baseline for monitoring posthurricane wetland recovery.

Damming the rivers of the Amazon basin.

PubMed

Latrubesse, Edgardo M; Arima, Eugenio Y; Dunne, Thomas; Park, Edward; Baker, Victor R; d'Horta, Fernando M; Wight, Charles; Wittmann, Florian; Zuanon, Jansen; Baker, Paul A; Ribas, Camila C; Norgaard, Richard B; Filizola, Naziano; Ansar, Atif; Flyvbjerg, Bent; Stevaux, Jose C

2017-06-14

More than a hundred hydropower dams have already been built in the Amazon basin and numerous proposals for further dam constructions are under consideration. The accumulated negative environmental effects of existing dams and proposed dams, if constructed, will trigger massive hydrophysical and biotic disturbances that will affect the Amazon basin's floodplains, estuary and sediment plume. We introduce a Dam Environmental Vulnerability Index to quantify the current and potential impacts of dams in the basin. The scale of foreseeable environmental degradation indicates the need for collective action among nations and states to avoid cumulative, far-reaching impacts. We suggest institutional innovations to assess and avoid the likely impoverishment of Amazon rivers.

Nature and origin of basin-forming projectiles

NASA Astrophysics Data System (ADS)

Wetherill, G. W.

The formation of the observed lunar multi-ring basins is discussed in the context of current theories of terrestrial planet formation, particularly those in which these planets formed by the accumulation of large planetesimals. The observed number, size, and timing of lunar basin-forming impacts is in the range expected for such theories. Tidal disruption during close encounters to earth and Venus can provide a single mechanism that explains a number of details concerning the number, size distribution, and stochastic nature of the timing of these impacts. A basin time scale is suggested in which Nectaris is associated with the 4.1 b.y. age of the Apollo 16 light matrix breccias. In accordance with the present consensus, Serenitatis is 3.86 b.y., Imbrium and Orientale 3.80-3.82 b.y. in age. Other nearside circular basins (e.g., Humorum and Crisium) are intermediate in age between 3.86 and 4.12 b.y. The large number of 3.8-3.9 b.y. ages is attributed primarily to the magnitude of the Imbrium and Serenitatis impacts, and sampling bias resulting from concentration of collection sites in proximity to these basins.

Assessing Mechanisms of Climate Change Impact on the Upland Forest Water Balance of the Willamette River Basin

NASA Astrophysics Data System (ADS)

Turner, D. P.; Conklin, D. R.; Vache, K. B.; Schwartz, C.; Nolin, A. W.; Chang, H.; Watson, E.; John, B.

2016-12-01

Projected changes in air temperature, precipitation, and vapor pressure for the Willamette River Basin (Oregon, USA) over the next century will have significant impacts on the river basin water balance, notably on the amount of evapotranspiration (ET). Mechanisms of impact on ET will be both direct and indirect, but there is limited understanding of their absolute and relative magnitudes. Here we developed a spatially-explicit, daily time-step, modeling infrastructure to simulate the basin-wide water balance that accounts for meteorological influences, as well as effects mediated by changing vegetation cover type, leaf area, and ecophysiology. Three CMIP5 climate scenarios (LowClim, Reference, HighClim) were run for the 2010 to 2100 period. Besides warmer temperatures, the climate scenarios were characterized by wetter winters and increasing vapor pressure deficits. In the mid-range Reference scenario, our landscape simulation model (Envision) projected a continuation of forest cover on the uplands but a 3-fold increase in area burned per year. A decline (12-30%) in basin-wide mean leaf area index (LAI) in forests was projected in all scenarios. The lower LAIs drove a corresponding decline in ET. In a sensitivity test, the effect of increasing CO2 on stomatal conductance induced a further substantial decrease (11-18%) in basin-wide mean ET. The net effect of decreases in ET and increases in winter precipitation was an increase in annual streamflow. These results support the inclusion of changes in land cover, land use, LAI, and ecophysiology in efforts to anticipate impacts of climate change on basin-scale water balances.

Air quality impacts of distributed power generation in the South Coast Air Basin of California 1: Scenario development and modeling analysis

NASA Astrophysics Data System (ADS)

Rodriguez, M. A.; Carreras-Sospedra, M.; Medrano, M.; Brouwer, J.; Samuelsen, G. S.; Dabdub, D.

Distributed generation (DG) is generally defined as the operation of many small stationary power generators throughout an urban air basin. Although DG has the potential to supply a significant portion of the increased power demands in California and the rest of the United States, it may lead to increased levels of in-basin pollutants and adversely impact urban air quality. This study focuses on two main objectives: (1) the systematic characterization of DG installation in urban air basins, and (2) the simulation of potential air quality impacts using a state-of-the-art three-dimensional computational model. A general and systematic approach is devised to construct five realistic and 21 spanning scenarios of DG implementation in the South Coast Air Basin (SoCAB) of California. Realistic scenarios reflect an anticipated level of DG deployment in the SoCAB by the year 2010. Spanning scenarios are developed to determine the potential impacts of unexpected outcomes. Realistic implementations of DG in the SoCAB result in small differences in ozone and particulate matter concentrations in the basin compared to the baseline simulations. The baseline accounts for population increase, but does not consider any future emissions control measures. Model results for spanning implementations with extra high DG market penetration show that domain-wide ozone peak concentrations increase significantly. Also, air quality impacts of spanning implementations when DG operate during a 6-h period are larger than when the same amount of emissions are introduced during a 24-h period.

Role of groundwater in formation of Martian channels

NASA Technical Reports Server (NTRS)

Howard, Alan D.

1991-01-01

A global 3-D model of groundwater flow has been used to study possible behavior of groundwater on Mars and its role in creating fluvial features. Conclusions drawn from an earlier 2-D groundwater model are supplemented and expanded. Topical headings are discussed as follows: timescales of groundwater flow; wet areas on Mars and location of outflow channels; implications for valley networks; the enigma of Hellas; absence of fluvial or periglacial features on Syrtis Major; development of chaotic terrain and associated outflow channels; and structurally controlled valley networks.

Using Lunar Impact Basin Relaxation to Test Impact Flux Models

NASA Astrophysics Data System (ADS)

Nimmo, F.; Conrad, J. W.; Neumann, G. A.; Kamata, S.; Fassett, C.

2017-12-01

Gravity data obtained by the GRAIL mission [1] has constrained the number and distribution of lunar impact basins [2]. We analyzed crater densities for newly-proposed basins to assign relative ages. The extent to which a basin is relaxed is calculated using GRAIL-derived crustal thickness models [3] by comparing the mantle uplift under basins to the surrounding region. With our catalog we can investigate the distribution of basin properties through relative time. We identify a relaxation state transition (RT) around the pre-Nectarian 4 relative age group for basins with diameters > 450 km, similar to previous results using a pre-GRAIL basin catalog [4]. This RT likely signals a change in the global thermal state of the crust, representing the time at which the lunar moho temperature fell below 1400 K [4]. This transition happens 50-100 million years (Myr) after the lunar magma ocean (LMO) solidifies [4]. Based on models and inferences of LMO solidification [5, 6] the RT is expected to occur at 4.25-4.50 Ga, depending on the rate of cooling once a crustal lid has formed [5] and the amount of tidal heating in the early crust [6]. Monotonically declining impact flux models, such as [7] and [8] predict a younger RT; 4.07-4.08 and 4.24-4.27 Ga respectively. A scaled-down version of [8] can fit the RT but fails to match the observed number of younger, unrelaxed basins. Models that invoke a later transient increase in impact flux can reproduce the inferred RT time; for instance, the model of [9] gives a RT age of 4.43-4.46 Ga. This model matches the number of younger basins and implies that basin preservation started at 4.49 Ga, likely before the LMO completely solidified. [1] Zuber M.T. et al. (2013) Science, 339, 668-671. [2] Neumann G.A. et al. (2015) Science Advances, 1, e1500852. [3] Wieczorek M.A. (2013) Science, 339, 671-675. [4] Kamata S. et al. (2015) Icarus, 250, 492-504. [5] Elkins-Tanton L.T. et al. (2011) Earth Planet. Sci. Lett., 304, 326-336. [6] Meyer, J. et al. (2010) Icarus, 208, 1-10. [7] Robbins S.J. (2014) Earth Planet. Sci. Lett., 403, 188-198. [8] Neukum G. et al. (2001) Space Sci. Rev., 96, 55-86. [9] Morbidelli A. et al. (2012) Earth Planet. Sci. Lett., 355, 144-151.

Lunar impact basins: New data for the western limb and far side (Orientale and South Pole-Aitken basins) from the first Galileo flyby

NASA Astrophysics Data System (ADS)

Head, James W.; Murchie, Scott; Mustard, John F.; Pieters, Carle M.; Neukum, Gerhard; McEwen, Alfred; Greeley, Ronald; Nagel, Engelbert; Belton, Michael J. S.

1993-09-01

Compositional aspects of impact basin materials can be analyzed using multispectral image data acquired by the Galileo solid state imaging (SSI) experiment during the December 1990 lunar encounter. These data provide important information on the spectral properties of the western lunar limb and parts of the far side. The SSI images cover the wavelength range 0.4-1.0 μm, allowing measurement of spectral slope and estimation of the strength of the 1 μm absorption due to iron in the mafic minerals olivine and pyroxene. Among deposits of the 930-km-diameter Orientale basin, exterior ejecta comprising the Hevelius Formation is relatively homogeneous and spectrally similar to mature Apollo 16 soils, suggesting an upper crustal source. The centrally located Maunder Formation is distinct from the younger mare basalts but comparable to the Hevelius Formation in its spectral reflectance properties, supporting an interpretation as basin impact melt. The Montes Rook Formation, located in an annulus between the Maunder and the Hevelius, shows a slightly stronger mafic absorption and may be the deepest crustal material excavated. The distal Orientale deposits show local mafic enhancements (in the Schiller-Schickard and Mendel-Rydberg regions) interpreted to represent pre-Orientale mare deposits, or cryptomaria, intermixed with overlying basin ejecta. In this case, maria of sizes comparable to those presently observed were widespread in this region before the Orientale impact. Mixing-model analyses are consistent with the ballistic erosion and sedimentation model for ejecta emplacement in the distal regions beyond the continuous ejecta deposit. On the southern lunar farside, a high area with an enhanced mafic absorption corresponds to the interior and rim of the pre-Nectarian South Pole-Aitken impact basin, 2000-2500 km in diameter. The anomaly is interpreted to be due to several factors, including excavation into the more mafic lower crust, and the presence of extensive early volcanic fill (cryptomare), similar to that seen in ancient basins such as Smythii and Australe. These results show that although basin-forming events are an important factor in producing lateral heterogeneities in crustal composition, and in modifying preexisting deposits (such as cryptomaria), the majority of material in even the largest basins was excavated from mixed crustal layer of anorthosite, basin ejecta, and cryptomaria deposits (generally corresponding to the megaregolith), an upper crustal layer of anorthosite, and a lower more noritic layer. Many of the basic questions remaining from this study could be addressed by global high-resolution geochemical and mineralogical data obtained by polar orbiting spacecraft.

Effects of basin-forming impacts on the thermal evolution and magnetic field of Mars

NASA Astrophysics Data System (ADS)

Roberts, J. H.; Arkani-Hamed, J.

2017-11-01

The youngest of the giant impact basins on Mars are either weakly magnetized or completely demagnetized, indicating that a global magnetic field was not present at the time those basins formed. Eight basins are sufficiently large that the impact heating associated with their formation could have penetrated below the core-mantle boundary (CMB). Here we investigate the thermal evolution of the martian interior and the fate of the global magnetic field using 3D mantle convection models coupled to a parameterized 1D core thermal evolution model. We find that the survival of the impact-induced temperature anomalies in the upper mantle is strongly controlled by the mantle viscosity. Impact heating from subsequent impacts can accumulate in stiffer mantles faster than it can be advected away, resulting in a thermal blanket that insulates an entire hemisphere. The impact heating in the core will halt dynamo activity, at least temporarily. If the mantle is initially cold, and the core initially superheated, dynamo activity may resume as quickly as a few Myr after each impact. However unless the lower mantle has either a low viscosity or a high thermal conductivity, this restored dynamo will last for only a few hundred Myr after the end of the sequence of impacts. Thus, we find that the longevity of the magnetic field is more strongly controlled by the lower mantle properties and relatively insensitive to the impact-induced temperature anomalies in the upper mantle.

Metagenomics Analysis of Microorganisms in Freshwater Lakes of the Amazon Basin.

PubMed

Toyama, Danyelle; Kishi, Luciano Takeshi; Santos-Júnior, Célio Dias; Soares-Costa, Andrea; de Oliveira, Tereza Cristina Souza; de Miranda, Fernando Pellon; Henrique-Silva, Flávio

2016-12-22

The Amazon Basin is the largest hydrographic basin on the planet, and the dynamics of its aquatic microorganisms strongly impact global biogeochemical cycles. However, it remains poorly studied. This metagenome project was performed to obtain a snapshot of prokaryotic microbiota from four important lakes in the Amazon Basin. Copyright © 2016 Toyama et al.

Crustal thickness of the Moon: New constraints from gravity inversions using polyhedral shape models

NASA Astrophysics Data System (ADS)

Hikida, Hajime; Wieczorek, Mark A.

2007-12-01

A new method is presented for estimating crustal thickness from gravity and topography data on the Moon. By calculating analytically the exterior gravitational field for a set of arbitrarily shaped polyhedra, relief along the crust-mantle interface can be inverted for that satisfies the observational constraints. As this method does not rely upon filtering the Bouguer anomaly, which was required with previous inversions performed in the spherical-harmonic domain, and as the dramatic variations in spatial quality of the lunar gravity field are taken into account, our crustal thickness model more faithfully represents the available data. Using our model results, we investigate various aspects of the prominent nearside impact basins. The crustal thickness in the central portion of the Orientale and Crisium basins is found to be close to zero, suggesting that these basins could have conceivably excavated into the lunar mantle. Furthermore, given our uncertain knowledge of the density of the crust and mantle, it is possible that the Humorum, Humboldtianum, Nectaris, and Smythii basins could have excavated all the way through the crust as well. The crustal structure for most of the young impact basins implies a depth/diameter ratio of about 0.08 for their excavation cavities. As noted in previous studies, however, the crustal structure of Imbrium and Serenitatis is anomalous, which is conceivably a result of enhanced rates of post-impact viscous relaxation caused by the proximity of these basins to the Procellarum KREEP Terrane. Impact basins older than Smythii show little or no evidence for crustal thinning, suggesting that these ancient basins were also affected by high rates of viscous relaxation resulting from higher crustal temperatures early in the Moon's evolution. The lithosphere beneath many young basins is found to be supporting a downward directed force, even after the load associated with the mare basalts is removed, and this is plausibly attributed to superisostatic uplift of the crust-mantle interface. Those basins that are close to achieving a pre-mare isostatic state are generally found to reside within, or close to, the Procellarum KREEP Terrane.

Cumulative impacts on seabed habitats: an indicator for assessments of good environmental status.

PubMed

Korpinen, Samuli; Meidinger, Manuel; Laamanen, Maria

2013-09-15

The European seas are under anthropogenic pressures impacting the state of water quality, benthic habitats and species. The EU Marine Strategy Framework Directive (MSFD) requires the Member States to assess the impacts of pressures and make a programme of measures leading to good environmental status (GES) by 2020. This study presents a method for assessing the quantity and distribution of anthropogenic impacts on benthic habitats in the Baltic Sea by using spatial data of human pressures and benthic habitats. The southern sub-basins were more extensively impacted than the northern sub-basins. Over the entire sea area, deep sea habitats were more impacted than shallower infralittoral and circalittoral habitats. Sand and coarse sediments were the seabed types relatively most impacted in the Baltic Sea scale. A comparison against tentative thresholds for GES showed that in the sub-basin scale only one third of the habitat types was in GES. Copyright © 2013 Elsevier Ltd. All rights reserved.

Assessing Hydrologic Impacts of Future Land Cover Change Scenarios in the South Platte River Basin (CO, WY, & NE)

EPA Science Inventory

Long‐term land‐use and land cover change and their associated impacts pose critical challenges to sustaining vital hydrological ecosystem services for future generations. In this study, a methodology was developed on the San Pedro River Basin to characterize hydrologi...

Seismic effects from major basin formation on the Moon and Mercury

NASA Technical Reports Server (NTRS)

Schultz, P. H.; Gault, D. E.

1974-01-01

Grooved and hilly terrains are reported which occur at the antipode of major basins on the Moon (Imbrium, Orientale) and Mercury (Caloris). Order-of-magnitude calculations, for an Imbrium-size impact on the Moon, indicate P-wave-induced surface displacements of 10 m at the basin antipode that would arrive prior to secondary ejecta. Comparable surface waves are reported which would arrive subsequent to secondary ejecta impacts and would increase in magnitude as they converge at the antipode. Other seismically induced surface features include: subdued, furrowed crater walls produced by landslides and concomitant secondary impacts; emplacement and leveling of light plains units owing to seismically induced "fluidization" of slide material; knobby, pitted terrain around old basins from enhancement of seismic waves in ancient ejecta blankets; and the production and enhancement of deep-seated fractures that led to the concentration of farside lunar maria in the Apollo-Ingenii region.

Lunar impact basins and crustal heterogeneity - New western limb and far side data from Galileo

NASA Technical Reports Server (NTRS)

Belton, Michael J. S.; Head, James W., III; Pieters, Carle M.; Greeley, Ronald; Mcewen, Alfred S.; Neukum, Gerhard; Klaasen, Kenneth P.; Anger, Clifford D.; Carr, Michael H.; Chapman, Clark R.

1992-01-01

Multispectral images of the lunar western limb and far side obtained from Galileo reveal the compositional nature of several prominent lunar features and provide new information on lunar evolution. The data reveal that the ejecta from the Orientale impact basin (900 kilometers in diameter) lying outside the Cordillera Mountains was excavated from the crust, not the mantle, and covers pre-Orientale terrain that consisted of both highland materials and relatively large expanses of ancient mare basalts. The inside of the far side South Pole-Aitken basin (greater than 2000 kilometers in diameter) has low albedo, red color, and a relatively high abundance of iron- and magnesium-rich materials. These features suggest that the impact may have penetrated into the deep crust or lunar mantle or that the basin contains ancient mare basalts that were later covered by highlands ejecta.

[Impacts of hydroelectric cascade exploitation on river ecosystem and landscape: a review].

PubMed

Yang, Kun; Deng, Xi; Li, Xue-Ling; Wen, Ping

2011-05-01

Hydroelectric cascade exploitation, one of the major ways for exploiting water resources and developing hydropower, not only satisfies the needs of various national economic sectors, but also promotes the socio-economic sustainable development of river basin. unavoidable anthropogenic impacts on the entire basin ecosystem. Based on the process of hydroelectric cascade exploitation and the ecological characteristics of river basins, this paper reviewed the major impacts of hydroelectric cascade exploitation on dam-area ecosystems, river reservoirs micro-climate, riparian ecosystems, river aquatic ecosystems, wetlands, and river landscapes. Some prospects for future research were offered, e.g., strengthening the research of chain reactions and cumulative effects of ecological factors affected by hydroelectric cascade exploitation, intensifying the study of positive and negative ecological effects under the dam networks and their joint operations, and improving the research of successional development and stability of basin ecosystems at different temporal and spatial scales.

Lunar impact basins and crustal heterogeneity: New western limb and far side data from galileo

USGS Publications Warehouse

Belton, M.J.S.; Head, J. W.; Pieters, C.M.; Greeley, R.; McEwen, A.S.; Neukum, G.; Klaasen, K.P.; Anger, C.D.; Carr, M.H.; Chapman, C.R.; Davies, M.E.; Fanale, F.P.; Gierasch, P.J.; Greenberg, R.; Ingersoll, A.P.; Johnson, T.; Paczkowski, B.; Pilcher, C.B.; Veverka, J.

1992-01-01

Multispectral images of the lunar western limb and far side obtained from Galileo reveal the compositional nature of several prominent lunar features and provide new information on lunar evolution. The data reveal that the ejecta from the Orientale impact basin (900 kilometers in diameter) lying outside the Cordillera Mountains was excavated from the crust, not the mantle, and covers pre-Orientale terrain that consisted of both highland materials and relatively large expanses of ancient mare basalts. The inside of the far side South Pole-Aitken basin (>2000 kilometers in diameter) has low albedo, red color, and a relatively high abundance of iron- and magnesium-rich materials. These features suggest that the impact may have penetrated into the deep crust or lunar mantle or that the basin contains ancient mare basalts that were later covered by highlands ejecta.

Impact of extreme precipitation events in the Miño-Sil river basin

NASA Astrophysics Data System (ADS)

Fernández-González, Manuel; Añel, Juan Antonio; de la Torre, Laura

2015-04-01

We herein research the impact of extreme rainfall events in the Miño-Sil basin, a heavily dammed basin located in the northwestern Iberian Peninsula. Extreme rainfall events are very important in this basin because with 106 dams it is the most dammed in Spain. These dams are almost exclusively used for hydropower generation, the installed generating capacity reaches more than 2700 MW and represents almost 9% of the total installed electrical generation capacity of the Iberian Peninsula, therefore with a potential impact on the energy market. We research the extreme events of rainfall an their return periods trying to reproduce the past extreme events of rainfall and their time periods to prove the proper functioning of the adapted model, so we can forecast future extreme events of rainfall in the basin. This research tries to optimize the storage of dams and adapt the management to problems as climate change. The results obtained are very relevant for hydroelectric generation because the operation of hydropower system depends primarily on the availability of storaged water.

Geographic Distribution of QCDs Around the Northern Plains Basins of Mars and the Relationship to Lowland Materials

NASA Technical Reports Server (NTRS)

Buczkowski, D. L.; Frey, H. V.; McGill, G. E.

2005-01-01

It has been suggested that quasicircular depressions (QCDs) without a structural representation in Viking and MOC visible imagery represent buried impact craters [1,2,3,4]. Topographic depressions will form over impact craters buried by a differentially compacting cover material because total cover thickness, and thus total compaction, is greater over the center of completely buried impact craters than their rims [5]. If this is the process by which QCDs form, then only areas of differentially compacting materials should have QCDs. Previous work has established that there is a relationship of surface relief to diameter for QCDs around the Utopia Basin [6]. The slope of the trend of this relationship varies depending on cover thickness, becoming steeper with decreasing thickness [7]. Comparing trendslopes of QCDs around different lowland basins might give us insight into the relative thickness of the cover material in these areas. We explore the geographic distribution of QCDs around the Utopia, Isidis and Acidalia basins and compare their location to geologic units and materials. We also compare evidence for relative thickness of cover material at the three basins.

Ecosystem services in Mediterranean river basin: climate change impact on water provisioning and erosion control.

PubMed

Bangash, Rubab F; Passuello, Ana; Sanchez-Canales, María; Terrado, Marta; López, Alfredo; Elorza, F Javier; Ziv, Guy; Acuña, Vicenç; Schuhmacher, Marta

2013-08-01

The Mediterranean basin is considered one of the most vulnerable regions of the world to climate change and such changes impact the capacity of ecosystems to provide goods and services to human society. The predicted future scenarios for this region present an increased frequency of floods and extended droughts, especially at the Iberian Peninsula. This paper evaluates the impacts of climate change on the water provisioning and erosion control services in the densely populated Mediterranean Llobregat river basin of. The assessment of ecosystem services and their mapping at the basin scale identify the current pressures on the river basin including the source area in the Pyrenees Mountains. Drinking water provisioning is expected to decrease between 3 and 49%, while total hydropower production will decrease between 5 and 43%. Erosion control will be reduced by up to 23%, indicating that costs for dredging the reservoirs as well as for treating drinking water will also increase. Based on these data, the concept for an appropriate quantification and related spatial visualization of ecosystem service is elaborated and discussed. Copyright © 2013 Elsevier B.V. All rights reserved.

Riparian Cottonwood Ecosystems and Regulated Flows in Kootenai and Yakima Sub-Basins : Volume II Yakima (Overview, Report, Appendices).

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jamieson, Bob; Braatne, Jeffrey H.

Riparian vegetation and especially cottonwood and willow plant communities are dependent on normative flows and especially, spring freshette, to provide conditions for recruitment. These plant communities therefore share much in common with a range of fish species that require natural flow conditions to stimulate reproduction. We applied tools and techniques developed in other areas to assess riparian vegetation in two very different sub-basins within the Columbia Basin. Our objectives were to: Document the historic impact of human activity on alluvial floodplain areas in both sub-basins; Provide an analysis of the impacts of flow regulation on riparian vegetation in two systemsmore » with very different flow regulation systems; Demonstrate that altered spring flows will, in fact, result in recruitment to cottonwood stands, given other land uses impacts on each river and the limitations imposed by other flow requirements; and Assess the applicability of remote sensing tools for documenting the distribution and health of cottonwood stands and riparian vegetation that can be used in other sub-basins.« less

Evaluating the Impacts of Urbanization on Hydrological Processes and Water Resources by Comparing Two Neighboring Basins

NASA Astrophysics Data System (ADS)

Shao, M.; Zhao, G.; Gao, H.

2017-12-01

Texas, the fastest growing state in the US, has seen significant land cover/land use change due to urbanization over the past decades. With most of the region being arid/semi-arid, water issues are unprecedentedly pressing. Among the 15 major river basins, two adjacent river basins located in south-central Texas—the San Antonio River Basin (SARB) and the Guadalupe River Basin (GRB)—form an ideal testbed for evaluating the impacts of urbanization on both hydrological processes and water resources. These two basins are similar in size and in climate pattern, but differ in terms of urbanization progress. In SARB, where the city of San Antonio is located, the impervious area has increased from 0.6% (1929) to 7.8% (2011). In contrast, there is little land cover change in the GRB. With regard to the underground components, both basins intersect with the Edward Aquifer (more than 15% of basin area in both cases). The Edward Aquifer acts as one of the major municipal water supplies for San Antonio, and as the water source for local agricultural uses (and for the surrounding habitat). This aquifer has the characteristic of being highly sensitive to changes in surface water conditions, like the descending trend of the underground water table due to over exploitation. In this study, a distributed hydrologic model—DHSVM (the Distributed Hydrology Soil Vegetation Model)—is used to compare the hydrologic characteristics (and their impacts on water resources) over the two basins. With a 200m spatial resolution, the model is calibrated and validated during the historical period over both basins. The objectives of the comparisons are two-fold: First, the urbanization effects on peak flows are evaluated for selected extreme rainfall events; Second, the Edward Aquifer recharge rate from surface water under flood and/or drought conditions within the two basins is analyzed. Furthermore, future urbanization scenarios are tested to provide information relevant to decision making.

Proximal Cretaceous-Tertiary boundary impact deposits in the Caribbean

NASA Technical Reports Server (NTRS)

Hildebrand, Alan R.; Boynton, Willam V.

1990-01-01

Trace element, isotopic, and mineralogic studies indicate that the proposed impact at the Cretaceous-Tertiary boundary occurred in an ocean basin, although a minor component of continental material is required. The size and abundance of shocked minerals and the restricted geographic occurrence of the ejecta layer and impact-wave deposits suggest an impact between the Americas. Coarse boundary sediments at sites 151 and 153 in the Colombian Basin and 5- to 450-meter-thick boundary sediments in Cuba may be deposits of a giant wave produced by a nearby oceanic impact.

Iron Abundances in Lunar Impact Basin Melt Sheets From Orbital Magnetic Field Data

NASA Astrophysics Data System (ADS)

Oliveira, Joana S.; Wieczorek, Mark A.; Kletetschka, Gunther

2017-12-01

Magnetic field data acquired from orbit shows that the Moon possesses many magnetic anomalies. Though most of these are not associated with known geologic structures, some are found within large impact basins within the interior peak ring. The primary magnetic carrier in lunar rocks is metallic iron, but indigenous lunar rocks are metal poor and cannot account easily for the observed field strengths. The projectiles that formed the largest impact basins must have contained a significant quantity of metallic iron, and a portion of this iron would have been retained on the Moon's surface within the impact melt sheet. Here we use orbital magnetic field data to invert for the magnetization within large impact basins using the assumption that the crust is unidirectionally magnetized. We develop a technique based on laboratory thermoremanent magnetization acquisition to quantify the relationship between the strength of the magnetic field at the time the rock cooled and the abundance of metal in the rock. If we assume that the magnetized portion of the impact melt sheet is 1 km thick, we find average abundances of metallic iron ranging from 0.11% to 0.45 wt %, with an uncertainty of a factor of about 3. This abundance is consistent with the metallic iron abundances in sampled lunar impact melts and the abundance of projectile contamination in terrestrial impact melts. These results help constrain the composition of the projectile, the impact process, and the time evolution of the lunar dynamo.

Reconnaissance survey of the Duolun ring structure in Inner Mongolia: Not an impact structure

NASA Astrophysics Data System (ADS)

Xu, Xiaoming; Kenkmann, Thomas; Xiao, Zhiyong; Sturm, Sebastian; Metzger, Nicolai; Yang, Yu; Weimer, Daniela; Krietsch, Hannes; Zhu, Meng-Hua

2017-09-01

The Duolun basin, which is located in Inner Mongolia, China, has been proposed to be an impact structure with an apparent rim diameter of about 70, or even 170 km. The designation as an impact structure was based on its nearly circular topography, consisting of an annular moat that surrounds an inner hummocky region, and the widespread occurrences of various igneous rocks, polymict breccias, and deformed crustal rocks. Critical shock metamorphic evidence is not available to support the impact hypothesis. We conducted two independent reconnaissance field surveys to this area and studied the lithology both within and outside of the ring structure. We collected samples from all lithologies that might contain evidence of shock metamorphism as suggested by their locations, especially those sharing similar appearances with impact breccias, suevites, impact melt rocks, and shatter cones. Field investigation, together with thin-section examination, discovered that the suspected impact melt rocks are actually Early Cretaceous and Late Jurassic lava flows and pyroclastic deposits of rhyolitic to trachytic compositions, and the interpreted impact glass is typical volcanic glass. Petrographic analyses of all the samples reveal no indications for shock metamorphic overprint. All these lines of evidence suggest that the Duolun basin was not formed through impact cratering. The structural deformation and spatial distribution pattern of the igneous rocks suggest that the Duolun basin is most likely a Jurassic-Cretaceous complex rhyolite caldera system that has been partly filled with sediments forming an annular basin, followed by resurgent doming of the central area.

Cumulative impact assessment: Application of a methodology

DOE Office of Scientific and Technical Information (OSTI.GOV)

Witmer, G.W.; Bain, M.B.; Irving, J.S.

We expanded upon the Federal Energy Regulatory Commission's (FERC) Cluster Impact Assessment Procedure (CIAP) to provide a practical methodology for assessing potential cumulative impacts from multiple hydroelectric projects within a river basin. The objectives in designing the methodology were to allow the evaluation of a large number of combinations of proposed projects and to minimize constraints on the use of ecological knowledge for planning and regulating hydroelectric development at the river basin level. Interactive workshops and evaluative matrices were used to identify preferred development scenarios in the Snohomish (Washington) and Salmon (Idaho) River Basins. Although the methodology achieved its basicmore » objectives, some difficulties were encountered. These revolved around issues of (1) data quality and quantity, (2) alternatives analysis, (3) determination of project interactions, (4) determination of cumulative impact thresholds, and (5) the use of evaluative techniques to express degrees of impact. 8 refs., 1 fig., 2 tabs.« less

A Comparison of Runoff Quantity and Quality from Two Small Basins Undergoing Implementation of Conventional and Low-Impact-Development (LID) Strategies: Cross Plains, Wisconsin, Water Years 1999-2005

USGS Publications Warehouse

Selbig, William R.; Bannerman, Roger T.

2008-01-01

Environmental managers are often faced with the task of designing strategies to accommodate development while minimizing adverse environmental impacts. Low-impact development (LID) is one such strategy that attempts to mitigate environmental degradation commonly associated with impervious surfaces. The U.S. Geological Survey, in cooperation with the Wisconsin Department of Natural Resources, studied two residential basins in Cross Plains, Wis., during water years 1999?2005. A paired-basin study design was used to compare runoff quantity and quality from the two basins, one of which was developed in a conventional way and the other was developed with LID. The conventional-developed basin (herein called ?conventional basin?) consisted of curb and gutter, 40-foot street widths, and a fully connected stormwater-conveyance system. The LID basin consisted of grassed swales, reduced impervious area (32-foot street widths), street inlets draining to grass swales, a detention pond, and an infiltration basin. Data collected in the LID basin represented predevelopment through near-complete build-out conditions. Smaller, more frequent precipitation events that produced stormwater discharge from the conventional basin were retained in the LID basin. Only six events with precipitation depths less than or equal to 0.4 inch produced measurable discharge from the LID basin. Of these six events, five occurred during winter months when underlying soils are commonly frozen, and one was likely a result of saturated soil from a preceding storm. In the conventional basin, the number of discharge events, using the same threshold of precipitation depth, was 180, with nearly one-half of those resulting from precipitation depths less than 0.2 inch. Precipitation events capable of producing appreciable discharge in the LID basin were typically those of high intensity or precipitation depth or those that occurred after soils were already saturated. Total annual discharge volume measured from the conventional basin ranged from 1.3 to 9.2 times that from the LID basin. Development of the LID basin did not appreciably alter the hydrologic response to precipitation characterized during predevelopment conditions. Ninety-five percent or more of precipitation in the LID basin was retained during each year of construction from predevelopment through near-complete build-out, surpassing the 90-percent benchmark established for new development by the Wisconsin Department of Natural Resources. The amount of precipitation retained in the conventional basin did not exceed 94 percent and fell below the 90-percent standard 2 of the 6 years monitored. Much of the runoff in the LID basin was retained by an infiltration basin, the largest control structure used to mitigate storm-runoff quantity and quality. The infiltration basin also was the last best-management practice (BMP) used to treat runoff before it left the LID basin as discharge. From May 25, 2002, to September 30, 2005, only 24 of 155 precipitation events exceeded the retention/ infiltrative capacity of the infiltration basin. The overall reduction in runoff volume from these few events was 51 percent. The effectiveness of the infiltration basin decreased as precipitation intensities exceeded 0.5 inch per hour. Annual loads were estimated to characterize the overall effectiveness of low-impact design practices for mitigating delivery of total solids, total suspended solids, and total phosphorus. Annual loads of these three constituents were greater in the LID basin than in the conventional basin in 2000 and 2004. Seventy percent or more of all constituent annual loads were associated with two discharge events in 2000, and a single discharge event produced 50 percent or more of constituent annual loads in 2004. Each of these discharge events was associated with considerable precipitation depths and (or) intensities, ranging from 4.89 to 6.21 inches and from 1.13 to 1.2 inches per hour, respectively

What Do Nectaris Basin Impact Melt Rocks Look like and Where Can We Find Them?

NASA Technical Reports Server (NTRS)

Cohen, B. A.; Petro, N. E.; Lawrence, S. J.

2015-01-01

The formation of the Nectaris basin is a key event defining the stratigraphy of the Moon. Its absolute age, therefore, is a linchpin for lunar bombardment history. Fernandes et al. gave a thorough account of the history of different samples thought to originate in Nectaris, with the upshot being there is little agreement on what samples represent Nectaris, if any. We are revisiting the effort to identify Nectaris basin impact-melt rocks at the Apollo 16 site, to model their emplacement, and to use these parameters to examine other sites where Nectaris impact melt is more abundant and/or more recognizable for potential further study.

Forest impact estimated with NOAA AVHRR and landsat TM data related to an empirical hurricane wind-field distribution

USGS Publications Warehouse

Ramsey, Elijah W.; Hodgson, M.E.; Sapkota, S.K.; Nelson, G.A.

2001-01-01

An empirical model was used to relate forest type and hurricane-impact distribution with wind speed and duration to explain the variation of hurricane damage among forest types along the Atchafalaya River basin of coastal Louisiana. Forest-type distribution was derived from Landsat Thematic Mapper image data, hurricane-impact distribution from a suite of transformed advanced very high resolution radiometer images, and wind speed and duration from a wind-field model. The empirical model explained 73%, 84%, and 87% of the impact variances for open, hardwood, and cypress-tupelo forests, respectively. These results showed that the estimated impact for each forest type was highly related to the duration and speed of extreme winds associated with Hurricane Andrew in 1992. The wind-field model projected that the highest wind speeds were in the southern basin, dominated by cypress-tupelo and open forests, while lower wind speeds were in the northern basin, dominated by hardwood forests. This evidence could explain why, on average, the impact to cypress-tupelos was more severe than to hardwoods, even though cypress-tupelos are less susceptible to wind damage. Further, examination of the relative importance of wind speed in explaining the impact severity to each forest type showed that the impact to hardwood forests was mainly related to tropical-depression to tropical-storm force wind speeds. Impacts to cypress-tupelo and open forests (a mixture of willows and cypress-tupelo) were broadly related to tropical-storm force wind speeds and by wind speeds near and somewhat in excess of hurricane force. Decoupling the importance of duration from speed in explaining the impact severity to the forests could not be fully realized. Most evidence, however, hinted that impact severity was positively related to higher durations at critical wind speeds. Wind-speed intervals, which were important in explaining the impact severity on hardwoods, showed that higher durations, but not the highest wind speeds, were concentrated in the northern basin, dominated by hardwoods. The extreme impacts associated with the cypress-tupelo forests in the southeast corner of the basin intersected the highest durations as well as the highest wind speeds. ?? 2001 Published by Elsevier Science Inc.

Fate of Basin-forming Impact Debris from the Moon

NASA Astrophysics Data System (ADS)

Schultz, P. H.; Bruck Syal, M.; Raskin, C.; Owen, J. M.

2016-12-01

Recent work shows that projectile sizes for basin-forming impacts at the Moon are larger than previously estimated [1]. This finding has implications for the source regions of Late Heavy Bombardment impactors as well as added contributions from debris generated by similar basin-forming collisions. At such large scales, portions of the projectile fragment survive without interactions with the surface and continue downrange along the original trajectory. Such a process most likely occurs for oblique collisions (< 35° from the surface tangent) by bodies larger than 10% of the diameter of the Moon. For the SPA collision, more than 20% of the impacting body survives as newly generated Earth/Moon-crossing objects [2]. Over time some of this debris may have contributed to a spike in impact craters 20-50 km in diameter. Here we model lunar impact basin formation using Spheral, an adaptive Smoothed Particle Hydrodynamics code [3,4], focusing on the dynamical fate of basin ejecta and projectile fragments. Models employ self-gravity for the Moon and impactor and include the Earth's gravitational potential. Large impactors and the Moon are each assigned a two-layer, iron core and forsterite mantle structure. The problem is initialized using hydrostatic equlibrium profiles for pressure and density in both the impactor and target. We begin by modeling debris (target and impactor fragments) ejected from the South Pole-Aitken basin impact and extend the analysis to the Imbrium, Orientale, and Crisium basin formation. [1] Schultz, P.H., Crawford, D.A. Origin and implications of non-radial Imbrium Sculpture on the Moon, Nature 535, 391-394(2016). [2] Schultz, P.H., Crawford, D.A. Origin of nearside structural and geochemical anomalies on the Moon. GSA Special Papers 477, 141-159 (2011). [3] Owen, J. M. ASPH modeling of material damage and failure, in: Proceedings of the Fifth International SPHERIC Workshop, 297-304 (2010). [4] Owen, J. M. A compatibly differenced total energy conserving form of SPH. Int. J. Numer. Meth. Fl. 75, 749-774 (2014). This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52- 07NA27344. LLNL-ABS-699382.

Extreme multi-basin flooding linked with extra-tropical cyclones

NASA Astrophysics Data System (ADS)

De Luca, Paolo; Hillier, John K.; Wilby, Robert L.; Quinn, Nevil W.; Harrigan, Shaun

2017-11-01

Fluvial floods are typically investigated as ‘events’ at the single basin-scale, hence flood management authorities may underestimate the threat of flooding across multiple basins driven by large-scale and nearly concurrent atmospheric event(s). We pilot a national-scale statistical analysis of the spatio-temporal characteristics of extreme multi-basin flooding (MBF) episodes, using peak river flow data for 260 basins in Great Britain (1975-2014), a sentinel region for storms impacting northwest and central Europe. During the most widespread MBF episode, 108 basins (~46% of the study area) recorded annual maximum (AMAX) discharge within a 16 day window. Such episodes are associated with persistent cyclonic and westerly atmospheric circulations, atmospheric rivers, and precipitation falling onto previously saturated ground, leading to hydrological response times <40 h and documented flood impacts. Furthermore, peak flows tend to occur after 0-13 days of very severe gales causing combined and spatially-distributed, yet differentially time-lagged, wind and flood damages. These findings have implications for emergency responders, insurers and contingency planners worldwide.

Geothermal heating in the Panama Basin and its impact on water mass transformation

NASA Astrophysics Data System (ADS)

Banyte, D.; Morales Maqueda, M. A.; Hobbs, R. W.; Megann, A.; Smeed, D.

2017-12-01

Geothermal heating is a driving force of abyssal water transformation. To quantify its impact at the basin scale, a hydrographic survey of the Panama Basin was carried out in 2014-2015 as part of the international project OSCAR (Oceanographic and Seismic Characterisation of heat dissipation and alteration by hydrothermal fluids at an Axial Ridge). The study shows that about half of the water entering the basin, which is connected to the Pacific Ocean only through the a narrow passage part of the Ecuador Trench, is converted to lighter water within just 200 km downstream of the passage. Of the resulting water, a staggering 90% is transformed by geothermal heating inside the basin, welling up into the ocean interior from a bottom boundary layer (BBL) that can be up to 1000 m thick. The geothermal forcing leaves an imprint in temperature-salinity properties hundreds of meters above the thick BBL. We present a conceptual model of the abyssal water transformation in the basin that incorporates these processes.

Impact of Clean Air Act Regulations on Nitrogen Fate and Transport in Neuse River Basin

EPA Science Inventory

This study investigated impacts of Clean Air Act Amendment (CAAA) NOx emissions regulations on the fate and transport of nitrogen for two watersheds in the Neuse River Basin, North Carolina, USA from 1990 to 2020. The Soil and Water Assessment Tool (SWAT) and the Community Multi-...

78 FR 35314 - Availability of Final Environmental Impact Statement; Bunker Hill Groundwater Basin, Riverside...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-06-12

... DEPARTMENT OF THE INTERIOR Bureau of Reclamation [A10-1999-6000-100-00-0-0-3, 3501000] Availability of Final Environmental Impact Statement; Bunker Hill Groundwater Basin, Riverside-Corona Feeder... proposed Riverside-Corona Feeder Project. DATES: The Bureau of Reclamation will not make a decision on the...

Impact of Clean Air Regulations on Nitrogen Fate and Transport in Neuse River Basin

EPA Science Inventory

We investigated impacts of Clean Air Act (CAA) nitrogen emissions regulations on the fate and transport of nitrogen for two watersheds in the Neuse River Basin. The Soil and Water Assessment Tool (SWAT) and the Community Multi-Scale Air Quality (CMAQ) models were used. Two scenar...

Impact of tides in a baroclinic circulation model of the Adriatic Sea

NASA Astrophysics Data System (ADS)

Guarnieri, A.; Pinardi, N.; Oddo, P.; Bortoluzzi, G.; Ravaioli, M.

2013-01-01